My original plans for my 'bolt were to find a 261, or dual carb and split the exhaust on my '59 235. The more I think about it, the 4200 is probably the way to go and I would be much more satisfied with the end result. Finding a wrecked TB and stripping the drivetrain may even be cheaper than rebuilding a 50+ year old drivetrain and trying to squeeze a few extra ponies out of it.