Would someone be able to tell me the depth, i.e. chasis to upper back length compared to chassis to lower back length. Its the slope from the fuel tank mounting area that I'm trying to judge as I want to fix my fuel tank in but don't want it to foul on the rear panel that I don't yet have.

hi is it an MK INDY

the back panel goes almost upright you could take your tank right up to the edge and it wouldnt affect anything I dont think

just lay the tank on the two strips(right at the start of the strips backend not front) and make some straps out of alloy strips

No its a book build, sorry I forgot to put that in didn't I? That kinda answers it though, cheers.