Will consider your common sense recommendation. Haven't considered Sniper EFI at all. Thanks

Wow, EFI conversion for $1k would be sweet if only USCG approved?

Not USCG approved as of now, even though the sum of the parts seem safer than a bucket full of fuel on top of the motor, lol.

This was a good little Q&A with Holley.
​​​​​​Converting Marine Engines to EFI | Holley EFI University | General Studies

I Guess I need to remember my goals here and stay on track...if the boat ran as great as it did except for that 4K misfire (if that's what it really was)...I would be thrilled.

side note/question: when looking at (even) Holley 's site and formula for sizing carbs, consider 502 cubes & max rpm of 5k...the general recommendation is <700 cfm. Why even consider 850 cfm? Sure wish I had made the effort to run it on the stand after re-marinizing the long block, but that was part of my thinking in staying somewhat stockish
and reliable. I would hate to throw on a $700 QF and find out it's something like a 25 year old fuel pump, or an ignition thing. I suppose that would rear its head in other scenarios. If it is in fact a need to calibrate (kit is $65) , which mode would I be trying to richen (power mode or cruise mode)? The misfire occurred by carefully inching up the rpm). I never even tried jamming throttle through that power band...just tapping to increase. I can see myself doing both the recalibrate attempt and ultimately replacing the carb (just sayin'). Once again thanks for everybody's info, I'm learning. Dave

Well, then check out all those items. There is only so much we can do behind a computer screen.

Remember when comparing cars to boats, a certain size might be fine on a car that sees 5000 rpm and or full throttle from traffic light to traffic light or the occasional blast down a back road.It sees that in a transient state. A boat motor may see that for miles, so it may just run at a steady state for a prolonged period of time what a car motor only occasionally sees. With carbs, valvetrain or anything else whats fine on a car motor may be marginal on a boat motor. Whats marginal on a car motor my be disastrous in a boat motor...

Alright already, I'm convinced. So Quick Fuel m-850? Will work well with the Edelbrock RPM AIR GAP?... and I'll place the order today and give you guys the weekend off...looks like I will I need some supporting parts...fuel line kit, and what about a fuel pressure gauge &/or regulator? Thanks

Throttle bracket. But I butchered a merc q-jet-afb one by cutting it off next to the left mount bolt. Works fine as an interim setup.

Where can that be had? Hopefully summit carries them?

https://www.summitracing.com/parts/sum-g1419