I still question that it's cheaper to do a V8, presuming that you are capable of doing more than just bolting stuff on.
The big things you need to buy for a good street motor are manifolds which are simple to build for a 6. True you can buy cams cheaply for SB's but there are also many grinders who will grind your cam for the same price.
I have no problem with your enthusiasm for v8's that's where most rodders are.
I'm restoring a 40 track roadster which came with a 270 GMC. These were the hot setup in the 40's and 50's. Finding parts is a standard problem for restoration/rodding of olde stuff.
What Bill Fisher said was before 100 million Chevy V-8's were produced,today a GMC cost per HP is 2 to 3 times that of a smallblock V-8 if you can find the GMC parts in the first place.
