OK,if I were you I would definatly go with the titanuim retainers(unless Simon has a good cheaper alternative) I would get the cometic HG and the ARP studs(no questions there) and have the head milled(make sure its an RA 50 or smoother) If the valves are leaking I would go with a good 3-angle valve job(especially on the exhaust side as the intake is radious cut stock) Make sure that before you get it milled you have the stupid oil hole welded up thats on the drivers side rear corner next that head bolt hole! If your head dont already have alum core plugs get some. There are two ways to go about that:#1,screw them in finger tight and weld them in. #2, Torque them in using some ultra black Permatex for a little "cushion" to 60 In/LBs
As for lifters,I have re-used stock ones a few times with no problems. If some are missing the little plastic retainer I would find some good used one to replace those. Cindy has a stash of good used ones that you could get from her if need be. But, if you have the cash go with the improved INA units. Just be careful when you are pulling them out of the rockers you dont lose any of the lifter discs!
As for the cams LWP stage1s would be a nice upgrade. I have not run any of these yet but talking to Wallace it sounds like they are worth about 50 HP. Getting them cryoed while you are at it a a very good idea. That depends or the rest of you setup alot tho also.
As for your I-staft,get the newest version of one and get that cryoed as well. You are gonna want to put new bearings in also. Every time I have had a TIII pulled down the bearing is on its way out. If you have the whole motor out getting the block decked is a good idea when using s Cometic HG also. Anyhow,long enough for now hope this gave you some ideas