Feel free to give me a call for a custom qoute. Thanks Laz for your support! I will be calling you the first of the week brother!

So is it possible to make my 454 into a 540 with just a rotating assembly and not a special block?

And the truth shall set you free. One word----Merc.

NO. You need a different block to make a 540. You can make a 496 with a 4.25" crank.
Eddie

For COST reasons wouldnt a procharger be better if it doesnt need to be refreshed? Seems like the cheapest way out...

Yes, you are correct. A Procharger would be the cheapest way to make 600+ hp with his current setup. It will work great and be very reliable if it is set up correctly the first time. That means programming the ecm, upgrading the fuel system, etc.
Eddie

1 st sell your motor, then I would go to classifieds under motors , there are 525 motors in there priced fair they have 520-540 hp , 2 illmors for sale 650 hp(ad says owner wants them gone now) plus others that would be turn key and ready go. Also dont forget next is differnt lower unit / then props/testing

my 2 1/2 cents

Gellner and Young both have your best piece of advise and people who can really help you get it right. For 600 - 700Hp reliable marine ENDURANCE performance engine you need just that, not some JEGS, Summit, GM Performance crate or parts basket , garage floor built marine ATTEMPT engine!
Set a reasonable budget as if you don't have the COIN you can't do it right to begin with so don't do it wrong and buy it TWICE!
It kinda scares me when I hear someone threw a crate 502 engine in some boat used it in NY in some small lake for two seasons, probably about 100-120 hours hours tops and now is having to turn it into a 552 something. That's not reliable "ENDURANCE" and sounds like they are into the BUY and BUILD IT TWICE MODE!!

Best Regards,
Ray @ Raylar

GenVI BBC are stout blocks, nothing wrong with a 454. I would do a centrifugal supercharger (procharger, etc.). Should easily make 600hp when you want it, and the rest of the time you won't even notice it's there. Probably not even in boost at cruise. Spend a few extra bucks to do it right.... make sure it's tweaked right, as someone mentioned on here. Maybe frsh headgaskets too etc.

On a side note, I'm all for cubic inches, but I'd rather have a 454 then a 496.
If you want more cubes, I'd bore to 502 rather than stroke to 496.
Also, aren't 454 and 502 the same block? ...9.8" deck/Gen6 BBC.
Both have 4" stroke but the 502= 4.47 bore and 454= 4.25 bore.

502 is a different block it comes with thincker walls to allow for the bigger bore

a stock GM block non bowtie is more than adequate for 600hp
Ive run a few stock GM 454 blocks that have made over 800hp so I would honestly not waste the money on an aftermarket block for the power level your shooting for

you could sell your motor complete and build a 540 inch motor with edelbrock, dart, merlin, afr (any decent aftermarket head) even really worked stock GM heads (but the cost is not really worth it unless you can do all the custom porting yourself) and make 650hp all day long realiably on pump gas without any power adder
its a pretty basic setup
if you need a good shop to build them for you pm me and I can put you in touch with one,
or check out some of the board advertisers on here,
any capable engine shop can build a 650hp 540 inch bbc motor
that combo and power level is really kind of mild