coil over angles

[surewhynot]

I recently installed the lt1 style rear brakes on my 1985 cutlass. II had to relocate the shocks, therefore i made my own bracket. The bracket itself is stable, but i do not like the look of it, and i just do not trust it (ocd/ overthinking in my head.) My question is, if i convert to coilovers, i was thinking of welding in a frame tie and mounting the upper mount to that, and making a new lower mount attached to the rear, what is the optimal angle to moun the coilover assembly to optimize handling? Thanks in advance