G 15 grt

Mods are coming back next year.... so a buddy has a grt with g15 welded on the rear frame... looking for some starting points.... found some generic set up sheets at grt but don't show a G15.....car was traded for race ready..... looks to have a combination of Old School set up / New School theory set up....looks old school rr spring, rf and lf... but a 125 16" LR with 1" load at full hike.... LF ride height looks to be about 2" high from ground to lower bolt if ride heights are still around 8" like other chevelle clipped cars.... Buddy is going to try and call grt and see.... Any recommendations before that happens ? thanks ahead of time