1.) What is the intended use of the car, cruiser, driver, dragster, etc.? 2.) What drive train does it have now and what changes are planned? 3.) What kind of shape is the exterior/interior? 4.) Does the car run - is it street or road worthy now? 5.) Welcome to the forum!
Uhhh a 8.8" comes close to strength of a 9"... Ones with 31 spline axles used in Hi-Po applications no doubt exceed the run of the mill 9" that used 28 spline axles...
Basically there is no real reason to swap in a sub 300Hp application and probably not with another 50Hp... Back in the day I did see several broken by high Hp 289 that could get traction...
Your going to want to use the explorer 8.8. Some come with 31 spline track-lok's and a decent gear. I used one and cut the long axle tube appx 2 3/4 in and ordered 2 short side axles.