turbo 273 parts collected now some ?s

Love the build, to answer some of your questions:

The camshafts mentioned in your postings are terrible, and not so terrible choices. I would look for a solid lifter camshaft with 112-115 LSA, and somewhere around 220-230* duration @ .050. Lift is important as well, but I would stick to around .500 (after lash) as the head flow isn't great after that point and their is no need to over work the valvesprings. What you are trying to achieve here is little, to no positive overlap.

I don't think you've talked much about your fuel system, but since you are budget oriented, a single Walbro GL392 (external 255LPH) fuel pump will meet your current demands. I would honestly purchase two, ran inline (not --, but =) and have one controlled via Hobbs pressure switch. This will meet all your current, and future fuel demands. -8an forward, and -10an return lines should be mandatory. This isn't power dependent, but fuel pressure and flow dependent. You'll have a terrible time attempting to keep baseline fuel pressure below 10 PSI without running a 5/8" (-10an) return line, as the flow with lower base pressures is much higher than with high base pressure EFI systems. -8an forward lines will meet all your power needs for the future, their is no reason to do this twice. Do it once with quality fuel line (Aeroquip) and be done with it.

Around 14PSI you should relatively make twice the power as your engine could produce without f/i. So, if the little 273 made 275HP you could expect 550HP at the crank if all goes well. You may want to look into basic methanol injection kits, or even build one yourself as they are pretty simplistic and you can gain massive power/per dollar with one. You don't want to leave anything to chance on the verge of detonation in boosted applications. You can build your own kit for $150-$200, google 'home made methanol injection kits'.

Sell the four speed and clutch package, stick with a 727 with a good manual valve body and converter. This is coming from someone who loved his four speed almost more than the car. It just doesn't work well in boosted applications, it may work at the lower power levels, but it is a risk making anything more than 600HP in durability. Even with liberty gear sets and twin disc clutches, it was not designed to handle the power forced induction engines create. You will end up destroying it more than once with any healthy dose of power, especially when you move up the chain to a healthy, boosted 360 based power plant. I was burning through clutches rated for 750HP at 6PSI.

Last but not least, purchase or download Corky Bells Maximum Boost. It is the 'bible' of turbocharging. It is easy for people familiar with turbocharging to ramble off statistics, give advice, and so on. It is better for you to decipher for yourself what is good, and what is not such great advice. This book will teach you everything you need to know about basic turbocharging.