Trying to turn my valken ASL tango into a pseudo DMR. I know I'll need a tight bore barrel and maybe a new hopup unit but what else can I do?

Try the DMR Holy Grail guide.

You don’t nesscarily need a tightbore barrel, as bore diameter does almost nothing to affect accuracy and range(tho most of the good quality barrels are tightbores lol), and you shouldn’t get a new hop up unless your current one is broken, as it won’t make your performance any better. Best to upgrade your bucking and nub to something like a maple leaf macaron 60° and omega nub, that’ll actually make your performance better