Not sure the math on stock compression vs. lower compression motors, but my boost it viper at 12 lbs pulls the same clutch setup as my headshim nytro with mcx 310 kit running 20-21 lbs
Haul 45 gallon drum regularly in trailer, had dot look in it as well as both sides at border crossing. No one has ever cared. Dot was surprised how much race gas sleds go through.
if it was bought in a company and he was reimbursed gst, he will have to remit gst when he sells it to you. whether it's added or he includes it in the price is between you two
You can get away without an adjustable boost controller (they're about $100) , you'll be set at whatever the rod length is set at. You can change boost manually, but it's a pain. You can not run without a fuel box of some sort. I'd suggest doing more research before you commit to buying.
I got rid of my ram 3500 due to multiple electronic issues which are frustrating when covered by warranty, and very expensive when bumper to bumper runs out. Also multiple front end issues and took out the headgasket.