Well you will definitely need a reg coming right off the scuba tank, otherwise it will be sending 2000-3000 PSI though your tubing, and that will probably blow most PVC. It would probably just be easier to use the scuba tank to fill other HPA bottles since they have the right fittings and regs already on them. I dont know much about setups like this, but you will need to regulate the air down before it sends through piping.
Why do people do this wanna-be hk thing? I mean hk people dont even play paintball, they just whine and start drama while wearing the ugliest stuff. Seriously you find light blue and pink to be attractive colors for your parents 1500 dollar investment (your gun/marker)? If you want to whine keep it off the field and save it for the internet; O wait! THATS EXACTLY WHAT YOU DO! Haha, if you don't play then don't whine.
I want your G6r parts and upgrades, sell them to me, because you wont get anything for them if you sell/trade them with the gun.