ya, it works
Sure, you can run the stock pipes and cdi with a 780, just keep the porting in line and not too much compression and they work good. If you want a king of the hill, take no crap 780, then your gonna need a set of bender big bore pipes and a set of bored carbs(or 38mm mach z carbs), and some compression and good port timing, I would also say a aftermarket cdi box.
What happens is with a healthy big bore, your gonna fill up the stock pipe more, with fewer pulses coming back to the cylinder, now add alot more compression, and what happens is the pipes will peak at a way lower rpm then when they were on a stock 700, this will show on a dyno at 7800-8000rpm, peak hp numbers, anything past that and its decreasing rapidly per hundred rpm intervals. This also applies to a race ported 700,more compression,etc. been there dun that already.