Not really you can get the 85-86 to have as much power. But the biggest benefit of the 87-92 motor is it has a external reed cage just like the Blaster. The 85-86 has one reed under the jug. Plus the 87-92 has alot of options for the exhaust, LRD, Dynoport, FMF, FTZ, Paul Turner and some I probaly missed. For the 85-86 you have FMF, AAEN that you can still get, but the AAEN you have to get lucky and find one on eBay or have them make you one new. I think there is a Koofman pipe to but not sure.
The pwer valve on the 87-92 arent like the powervalves on modern bkes, it is more of just an exhaust valve.