With your mods and most street level blowers in the 8-9psi range, you're looking at anywhere from 330-360rwhp. And like Slick96 said, add a few breathing mods like the PI intake and spend a few bucks and have your NPI heads ported, saddled with a set of PI cams and some added boost, 400rwhp shouldn’t be too hard to surpass.
well that depends, you can have a totally recked and warn out motor in 20,000 miles if its been abused and mistreated.
Having said that 127,000 is quite a few miles, you best bet would be to over haul and rebuild your engine (it would then be like a recondidtioned unit), but until you strip it down you won't know how much work it will need.
Buy a low milage 2nd hand engine and hope for the best (or rebuild it it instead), or buy a new short block and make an essentially new engine out of it and as many parts from your current engine as you can.
There is no cheap option though, you could slap the blower on and hope for the best, if it runs well it might be ok for years to come, but then again it may not.
If your gonna rebuild an engine it would be worth improving it with forged parts so as to handle the boost better.