I ran a P-1SC 10# kit for a year on a stock bottom end on my 99. I used the UNIVER MAF and 42s like SLOBRA says, also as he says on the D-1SC keep 10#s no more to play it safe. Same injectors will work. Go with the 2003 fuel system (tank and dual pumps) now, verse playing the game to find a fuel pump setup. I tossed the ATI supplied fuel pump and used 2 pumps before I was happy.
When you forge the bottom end and now want to run 15# plus do as SLOBAR also says, upgrade to 55#s. The 2003 fuel system will now work just fine too.
I did this exact thing see sig. Also, when you have the bottom end forged , and the engine is out, save some $$s for long tubes. I di d this. The one thing I want to do still is port the upper and lower intake now. My goal is 600 RWHP.
BUT, BUT,,,,I will give up on the IRS, sorry. I got a ton of receipts for $$s spent on trying to fix the wheel hop and getting expensive half shafts, that I am done and beaten. The wheel hop fix is a mirage. I suggest you re-think that one. The power you will generate will give you some more clues, but take it from me. Solid Axle her someday.
John