Best way to tweak engine? Exhaust/t-bar clearance

Last year I fab'd up my own downpipes to come off my Hedman Tight Tubes and hook up to my existing Pypes dual exhaust setup. The pass. side pipe was really close to the torsion bar so I dimpled it a bit and it was OK; now about a month ago I finally took it to an exhaust shop and got everything welded up as it was just clamped together before. Now it rubs against the t-bar just enough to make an incredibly annoying vibration and noise. I'm thinking I just need to raise up the driver side of the engine a tad to move the pipe down and away from the bar.

I've read these other threads about header fitment issues and people using shims and other techniques; how much play is actually in the mount brackets and the mounts themselves? And what do the shims look like, are they flat plate-type deals that just go under the mounting pads? I have my original 1970 K-member btw with biscuit mounts.

My main concern is when I go to put in a bigger cam and the engine starts to shake more at idle (it's really smooth now) I want as much clearance as possible without making the engine super crooked to one side.