right i have a piper 285, i got a vernier pulley with this to get it set up right but i'm still sure it could be done better! i had to use the lifters as they were alot shallower than the standard ones. as the 285 is a bit more lairy you may get away with it on a 276. you should be able to buy them on their own, not just in kits if you did want to do it this way. i bought a kit as i thought it would be best to fit the lot all at once.
as for chipping it, you've done all the right things so would make sense to get it chipped/re-mapped, its on my to do list once my engine is run in. basicly chipping should be the last thing you do as ideally you should get it done to suit the mods you've already made. the best way to do is take it to a place with a rolling road and get them to set it up on the rollers. it'll cost a bit as it can take a while to get it right but i'm not convinced by a generic chip to do the job. its what i'm gonna do.