If your kips are locked open you will loose the smooth transition of your power delivery.
The engine will roll on then suddenly hit faster with power which is fine for drag racing or hill climbing, but not so good for much of anything else.
Boyesen's are good for making power lower in the RPM range whereas the V-Force reeds make power up higher in the rpm range.
I've never ran the round slide on a 500 so I have no comment there but there should be a few on this site with that experience.
-Wossner 86.50mm bore piston kit - Good
-Wossner or OEM connecting rod kit - Good - get your crank balanced..
-Cometic gasket kit - Good
-All balls cranks kit - can't comment on that, I use OEM or comparable German, British, US, Japanese, Swiss, no Chinese bearings
-Boyseen Rad valve - Boyesen's are good for making power lower in the RPM range whereas the V-Force reeds make power up higher in the rpm range.
So that depends on what you are wanting the engine to do, which pipe, ect.