I had my 8" welded up, I ended up breaking it due to excessive wheel hop (in fact, that was the last time my '65 ran), but doing it doesn't require any disassembly other than pulling the chunk and throwing it into a parts washer when done to clean out weld bb's and flux. If you're eventually going to upgrade to a 9", I see no reason not to do this, especially if you have a pretty stock engine.
It's old school, but it works. I have a friend with a '67 with a 9" and probably a 275HP 302 with a C4 and it's had a Lincoln Locker with 3.91s for over 15 years and not broken it. You have to be careful with corners and wet surfaces, tires wear faster. But when they break, the third member is typically toast, my caged bearing that supports the end of the pinion broke out of the support of the carrier, but the car still peg legged and I drove it up onto the trailer at the track and drove it a mile home from the shop when we got back to town.