98 30 valve aha........

long story on how i got to this point but I have finally found the culprit to a misfire after timing rebuild. found a slightly bent valve on the #6 cylinder (exhaust middle)
. no piston markings whatsoever, clean and smooth. I tweaked the bent vavle here and there and after several hundered cranks of the cam it seats perfect and "pops" in and out as it should. what are the chances this will work in the engine? once bent - always bent?
I assume there is no way to replace one valve without a huge hastle is there?
any input welcome!
about to order 8 new polybolts as I've read "don't re-use em", and a new head gasket. what about the intake gasket? seems fine but do those get trashed in the process as well?
what is the small yellow cone (looks like a parcheesy peice for us old fks) that is (was) connected to the intake?
any other advice on parts/gaskets relating to this?
also before i took the head off and was checking my timing i noticed the belt sliding out and off the roller and in turn rubbing the plastic timing covers. what gives? I've put in a new belt, rollers, water pump and thermo (the origional f'n prob) fan clutch, maf sensor,
coil pack, wires and some other bs trying to isolate the misfire.
guess I have some spare parts now.........
yes i have a scanner and tried 4 others and always got "communication error" after error making this one long mf to diagnose for the average garage joe......