Slant 6 Turbo... Tight quarters. I could use some pointers

You don't HAVE to mount the turbo up high. If you are just going for the turbo noise, mount the turbo further down the exhaust system where you have tons of room, and use a scavenge pump to get the oil back to the engine. Having the turbo further back will give you the "sounds" you are wanting. Google "rear mount turbo".