Go with the s-10 28 spline axles a open 28 spline carrieer and a mini spool and run the car at the track to see where you are at. Those parts are CHEAP and can be resold pretty quickly IF needed. We just ran our little monza with the sbc 377 destroked to 10.60 1/4 miles( 6.72 1/8th ) and it is a STOCK 8.5 s-10 rear ladder barred Full spool 4.10 with STOCK GM axles c-clip eliminated. 1.41 60 foot on 8x 26 MT slicks...lol.
I am sure you will be fine with the 7.5 for a bit as long as you do not dum p the clutch at over 4000 rpms etc.
I ran mini spool and 26 spline s-10 axles to 11.90 then got suggested to upgrade the seat belts and cage etc. lol.
Good luck. Jim
JD