I'll side with pat & 196 - both have valid opinions .......

IMO the block fill will stableize the thin wall block you created. I'd say .100 to .125 will be detrimental should you not utilize it. Anytime - race or not.

I'd also say if your trying to squeeze 1 HP per CI your looking for a window repair the first time that gem gets a bit of real heat in it.

I've run a 54 + .100 with good success with big comp. (14.1 to 1) & an older set of pro stock heads (EPD) & carb. intake running a clutch.

What I wouldn't do is spend a ton of cash on this combo as over time it will self distruct.........IMO. Find a solid 283-350 block & blow it over .060 - that'll last 4ever.

REGS