[PONTIAC DUDE]

Originally Posted by mgarblik

If you decide to go with an aftermarket block like the IAII, I would throw my vote in for a 541. The 4.375 bore and the 4.5" stroke is super sweet and many different combinations have been built for years now. I often felt that if I still had my 66 2+2 convertible, at 4270 Lbs., this is THE engine I would build for it. It was a blast with the 421 HO, but oh what another 120 CI would have done for it! 541's are easy and with the low cost Chinese cranks are not too expensive. A 600+ HP engine that would idle smoothly at 850 RPM,s and tear your neck off your shoulders with all that torque sounds like the ticket to me.

X2, but keep the bore at 4.350 w/4.5 stroke and then would be 535 cu.in. Just a little better gasket seal & room for next bore.
Just got a call yesterday from my buddy Paul and he finally got to take his car out. 67 droptop GTO with a 535 and my little 230/236 Butcher cam. Say's it idles like a champ and will tear the hides off his tires. LOL. about 550 hp but plenty of room to cam upgrade later if he wants to.

66 bonne is running one of my stock block 455's (4.185 bore) with a 4.5 crank.
65 Catalina and running 10.70's on pump gas and my custom hyd roller. So far.