Hi spog1......looking for a 'restored' pre' 73 big block Vette eh?.......good luck - hope you have a deep pocket and are happy to wait a long time for the right car.
Firstly let me comment relating to common misconceptions relating to the weight of big block Vettes.......so yes, a small block Vette has almost perfect 50/50 front rear weight distribution......but don't think that even a 50/50 balance will give impeccable handling......it won't. It may have (what is now regarded as being rudimentary) IRS which certainly improves handling and traction.......but can still 'snap-out' suddenly under extreme usage.
A big block Vette engine is certainly heavier, perhaps as much as 150 lbs more than a small block depending on options.......so it will come as a big surprise to many that a 68' to '72 Vette with ally heads, manual box, no power options can perhap be only 50/80 lbs more than an equivalent small block car and perhaps with a 49.50/50.50 'balance at best.....and ranging to 52/48 worst case scenario if equiped with auto, all power options and a/c.
Compared with other American muscle cars of the day (remembering that 69/70 390cu in/428cu in Mustang balances at 56/44) they still have a far better front/rear 'balance' than any other Yank or many V8 powered European car. The last of the BB Mustangs ('71 429 CJ actually had the best 'balance' of any BB variant.....despite the bulk and weight). Unfortunately there is a school of thought that a big block Vette is going to break the bank in terms of fuel costs.......and yes 15/16 mpg on cruise is challenging on the pocket........but so is the typical 18, perhaps 20 mpg of the eqivalent small block. Yes, my Vette is a 'stroker' ........you'll see the power figure at the bottom of my page 'signature'......yet can still pull 16 mpg on cruise.