I run a PG, works great, should solve your cv breakage problem. You'd have to run an adapter plate to mate the L28 bolt pattern, no matter if you went th350 or PG, same tranny bolt pattern. There is not that much difference in gear ratio's, 2.54 first gear 1.54 for second in the th350, I think, and 1.76 or 1.82 for the glide unles you go to custom gear set then you can get into the 2's for a low gear. High gear is still 1:1. So, it's like inbetween 1st and 2nd gear on a 350. The 1.82 set would handle about all the L6 could put out, but if it's a v8 I'd go with the stronger 1.76 gear set. Both are interchangeable as a unit. If you get a turbo splined input shaft then converters are alot cheaper and you can buy/sell easier. Also more durable than the stock input shaft.
The glide weighs about 110 to 120 with converter, mine does at least, so there is some weight savings, also there is some HP savings as well as the glide doesn't soak up as much HP as the 350 or 400.