I stumbled across a cache of 427 Truck blocks yesterday. Bought one, and getting the rest next week. I was working the math last night, and discovered that with a tall-deck truck block, a 4 1/4 stroke crank, and 6.385 rods, standard pin height 454 pistons could be used. They would wind up about .040-.045 in the hole if everything is at blueprint dimentions. I don't figure I can use a sheet of reynolds wrap for a head gasket like I did on the Tecumseh twenty years ago. To preserve quench, I'd have to have the block decked.

Will carving .045 off the decks weaken them? How much is safe to remove from a non-Bowtie big block?

Would I be better off having the deck shaved .025 and using a .020 shim head gasket? How much power will the shim gaskets take? (I know the LS-6 454 used shim gaskets.)

Have you bought rods or pistons yet? If you haven't you can use a standard 496 pin height piston(1.270) and some 6.8" long rods that are readily available and not have to worry about decking the block so much. You could also use the 496 pistons made for stock length rods(1.520ch?) and use a .400 longer rod(6.535).
The 6.8 would give a rod/stroke ratio of 1.6
The 6.535 r/s ratio would be 1.537
The 6.385 r/s ratio would be 1.50
Stock 454 r/s ratio is 1.533

Using the 1.270ch will give you more piston choices depending on what kind of compression you want to run as will a stock 454 piston, but would eliminate the piston being .045 in the hole. The 1.270 w/ 6.8" rods should leave the pistons .020 in the hole if true deck height is 10.2". I believe eagle and scat both offer the 6.8" rods at the same price as the shorter ones.
I thought about going this route before I found my standard height block to do my 496 with.

I don't know the answer to your question about being able to deck the block .045, but it seems that this would be more of a hassle by having to mill the intake and possibly have a weird length pushrod. It could possibly be more reasonable in the long run to get piston/rod combo closer to the top of the block.
Caleb

custom headers.....

I'm useing a Truck Block w/ 4.250 crank and went with a JE shelf piston for that stroke and a 9.800 deck height and used a 6.535 rod. Also useing Brodix heads and Hooker 2 1/8" headers, drivers side fits perfect, Passenger side I had to notch the frame for them to fit. It didnt require to much work, was able to do it in less than an afternoon. With heads that use a std. exhaust port location it would have required less work. As the taller deck and raised ports moved the header up and out.

Still looking for advice on decking "about" .040-.050 from a 427 truck block. (not bowtie block)

I'm hoping to use a standard, readily available (cheap) 454 flattop piston. If I have to go to a special design, I will.

Headers are not a concern, nor is power brake booster clearance. No brakes on a boat!

I found out today that GM sold 6.405 length rods many years ago. Yeah, that'd fix a bunch of problems with pin height!

Custom pushrods are just an accepted fact of life. They're the last part I order for an engine. It would be a miracle if I used standard length truck pushrods.

Manifold spacers and the extra-long distributor are the biggest bummers of this deal. My heads don't have exhaust crossovers, so I could either buy Weiand's spacers or build my own out of phenolic.

Can't see it being a problem but with that much off the decks nothing else will fit.

ttt

I think you're better off buying pistons that fit right rather than chopping up a block to fit pistons. Also, Mike is right, nothing is going to fit right on that block. By the time you get the manifold, distributor and whatnot to fit right it might be cheaper to get the right pistons to begin with. You can sell the pistons you have too.