I think if you already have a great running and skiing ZO boat why repower? if your SBC has hi hours, long block base engines are still available through many outlets except Pleasure craft marine.
as far as 6.0 in the 196 model. we'll! they ski pretty sweet! use a 668 ACME....
I am finishing up a 196 rebuild and had both a small block Excalibur and a zr6 on crates. I chose thr Excalibur due to the fact I ski 32 mph now, my wife 30 mph, my daughter a small women 2 overall skier and stephen,,,, well he seems to be able to ski behind anything and do well... we just did not need the 6.0 for what we do...
I picked up a 89 Master craft that the 6.0 is going in...... more on that project next month...