The ebay headers are for 86/87 and will NOT work for your hotair.Ever.
You can use your LT1/LS1 MAF if you buy a MAF Translator.I've got one and it works really well.Plus you can use the translator to help tune.I like mine.
Now...I know you're enthusiastic about getting started on your performance build...BUT...
...You really need to reread what we're saying here about what mods to put on when.You won't need injectors til you get quite a way down the performance road
.
If you don't have the right plugs at the right gap your car will run like crap.
If you don't have a Walbro pump you will detonate and kill your motor.
If you don't have a scantool you won't know what the hell is going on with anything.
There are a lot of us who have been down this road already and we're trying to help you take the quickest path to where you want to be.
As far as building the motor later,basically all a turbo shortblock has to do is not blow up
.There's really not much exotic to be done with these motors and your cam selection is pretty small compared to most other motors.