Tony;
Tough question, I can see why you are struggling with the decision.
A couple of things to consider:
--as Clois mentioned, a BB is tight to do work on. I replaced my valve covers this winter, and had to literally "fabricate" a tool to reach the back/bottom hold-down bolts.
--BUT, I do like the sound/torque/2x4's, etc---I do agree with you on that one.
--Might not want to take the chance to "compromise" your already pristine car by ripping it to pieces and making it swallow a BB, only to be not completely satisfied with the end result? Maybe tear up more in the process? Paint, etc.
--I think if you REALLY, REALLY want to go this route, I would sell your very nice SB, and start from scratch---this way you control the process, and it's all designed for the BB to start.
--Order a Kirkham like TC, get the BB and aluminum shell
It's a tough decision. You have the beautiful redhead today, but you may never really be satisfied until you get that Big Blonde (BB).
Best of Luck in your decision.
BigEasy
Charlie