89 supra turbo mods

[bbullsj]

i have an 89 supra turbo automatic. i blew the head gasket externally so im ripping it down. i was wonder what some easy options for upgrades were? everything is stock on it except for 3 inch stainless exhaust from bottom of manifold and back. ive heard swapping out the cams for n/a ones? does the timing need to be set differently than stock then? twin turbo setup(which would be costlty and prob some custom fab work)? aftermarket exhaust manifold that will still bolt up to the stock ct-26 turbos?
im not looking to get into fuel injectors, pump, and ignition yet. need to get it back driveable first but looking for some easy upgrades while im doing the head gasket.
are valve seals fairly easy to do or do they require some special tools?

it is currently an automatic but im hoping to convert it to a manual soon. i know i should just buy one thats a manual and same myself a lot of time but this car is in such good shape with no rust and ive put a lot of new parts on it in the past 2 years that i dont want to have to do to a new one.
if anyone has some good info or knows any sites or other threads that will help me it would be greatly appreciated. ive seen some other threads discuss upgrades but one always seems to contradict each other on which ones are the best.