Ya live and learn. That's why I try to fix my own chit now. But thanks for your input

Thanks for help guys, hope to start on this project soon.

Sounds like a good upgrade. The a1000 wants a -10 feed though, pump cools with fuel which I believe is why they want that -10 feed and requires the return. It also has tight tolerances which is why they want you to run the 100 micron filter, I personally ran their 100 micron pre filter. Also ditch the Merc fuel filter head and grab a sea choice 3/8 port one, it looks like the Merc filter head, but has the bigger 3/8 plumbing. if your return is under 6ft you may be able to run a -6 if it's all full flow (90 degree full flow hose ends instead of 90 degree fittings), otherwise gotta run a -8 return. I made the mistake of running a -6 to my fuel fill hose, was about 15ft, and I couldn't get my pressure to come down enough and stay stable, went to -8 and fixed that issue. Granted this was on a blower carb app, but going to the -8 allowed me to take my pressure down wherever I wanted it and it would stay that pressure from idle to wot. Good luck with it.

What about using the Bosch 044 or the Walbro 416?

Thanks great info, thinking the a1000 would be way overkill for my engine or any foreseeable upgrade. was going with the tsunami or a750 pump. was thinking of getting rid of the merc filter head and just using the 100 micron pre pump and 10 micron post pump. Up in the air about not having a water separator, always run non ethanol premium fuel from a trusted source, but will look into that filter head for extra protection. Thinking I have extra bung at the tank for a return which would be less than 6 feet for the return, but might be to close to the pickup and cause air bubbles. Thinking -8 for the feed to the pump and -6 to feed the rest and for the return, good head's up if I can't keep the pressure down.

Did you guys keep the antisiphon or is it too restrictive?

The walbro looks like a internal pump? but the bosch looks doable but doesn't have the bling factor but it is about a hundred bucks cheaper....

Been thinking about replacing my first Gen cool fuel but don't want to replace all the fuel lines to AN-10. Currently have 530HP using full 3/8 ID tube pickup, hoses and AN-6 fittings at 40psi and return back to the tank. Reading the aermotive 1000 says it needs larger hoses and fittings.

have not run a water separator in years with no issues, and I always remove antisiphon valve as its way to restrictive

I did this to my '93 502 mags and it should be considered a must for any of the vst equipped engines.no more problems. period.I just extended the existing factory wires that hooked the VST hp pump to my a1000 pump mounted low on an outside stringer, I personally ran the big ramco/FST/merc racing for a pre filter, the aeromotive 10 micron after, -10 xrp pushloc supply ,-8 out of the pump to the 10 micron, -6 for about 6" to fuel rail. soldered a -6 male bung onto a piece of the factory stainless fuel line with its captive o-ring connection to the rail. simple and easy.
Check out a cool fuel equipped engine and there's a nice brass plug that blocks the return passage,.goes in the back of the rail mounted regulator. then just you have a rail damper . which is good. I drilled and tapped the rail 1/8 npt to plug the passage to the regulator. not so good. also be sure to open up the #7 injector port while your at it.its like 1/8 " probably ok for stock but it looks funny compared to the rest that are about 5/16
I ran fuel into the back of the rail, out the front thru the 1/4npt port for the test port to an a1000 regulator . With the double returns to the tank filler hose , I constantly had a fuel smell, so I pulled the fuel sending unit and installed bulkhead fuel cell fittings for the return lines just to the side of the sender where I could access the nuts. those fittings seal with teflon washers so no leaks. be sure to put a aeromotive check valve on the pump outlet , I didn't and it will start faster and cleaner after sitting a while if you do. the VST cost me two motors this aeromotive upgrade is pretty cheap...... but it does take some rigging.

Well there you go I put a A1000 on around eight years ago first for fuel injection now it runs a carb app. with return to the tank. Has worked flawless except if left to sit for long time I have jump the relay for the pump to fill the carb [ takes too long to crank the motor because it runs thru a oil pressure switch]

No check valve.................good info thanks