Going to put some heads on my 99ta. Already have ms3 cam, dual springs, pushrods ext for the cam. Just adding heads. What parts do I need or shoudl I upgrade?

You need new head bolts as the factory ones are Torque To Yield ( non reusable)

Alot of guys upgrade to ARP Bolts at that point.

P/N 134-3609 in stock if you need, $150+ shipping

Head gaskets of course, Id maybe put some new lifters in since you're there already.

Ls7 lifters?

Yes LS7 Lifters seem to the preferred choice, thats what I used.

cool. so...
ARP head bolts
Head Gaskets.....GM MLS 01+??
ls7 lifter
oil and filter

need valve cover gaskets?

the valve covers have removable o-rings. You should be in good shape with them.

This is what I would get:

ARP Head Bolts
LS7 Lifters w/ LS2 Lifter Trays
GM Head Gaskets
GM Exhaust Manifold Gaskets
GM AIR Gaskets

Oil and filter
Dexcool Coolant