Supercharger...beef up lower end first?

I have 10-11 lbs boost at 6000 RPM or more (sometimes twist it to 7000) on a stock bottom end 89 engine that had over 100K miles on it. 122 MPH 1/4 mile. No problems BUT my mixture is good.

Should be fine, just don't push the boost too crazy. Also get a really good tune to keep things safe.

+1 Good tune and keep the Boost to 10 psi or lower.

10 psi is the grey area but most people run that with no issues.:bigthumbsup

I figured I'd get the lowest boost available to be safe.
Okay, might be a dumb question, but I'll ask. I've done plenty of tune ups on old cars, but when y'all mention 'keep a good tune,' what exactly does this mean? The 5.0 I have is totally stock, top to bottom.

Stay on top of the A/F ratio, is the just of it.

a good tune(on a supppper basic level) would refer going to a tuner where they strap your ride to a dyno where everything the car is doing is monitored (rpms, exhaust gas temps, ignition timing, air intake levels etc) just about evvverything is watched and after a few hours and many runs the tuner sets everything (a/f ratios, timing, etc..)to its peak efficiencency while staying within the safest limits.. so this creates the most efficient car while keeping the car from destroying itself (well as much as possible anyway) this is also the best way to get the mosssst out of your mods check out some dyno runs on youtube they are kool and probably pretty informative but they wayyyyyyy better in person!:bigthumbsup

stay on top of the tune and you will be good at 8-10psi boost

DEFINITELY upgrade your fuel system with a higher flow in tank pump as well as an external inline one like the T-Rex!
Bigger Injectors,Colder Plugs, Boost Retard Ignition Box,A/F in the high 11's and you'll be good to go:bigthumbsup