Dougs do a 2"header , not sure if it has a low deck version . I have the D452 on my RB .
You will need a big cfm carb , probably easier with a 4500 . I use a 1050 on a Super Victor .
Roller cam choice , cant help i use a solid flat tappet for durability . Maybe look at a custom with a softer ramp if street driving .
Tq well you have a stroker so should have enough especially against a clutch . Cant help with that i run a TF .
As to conservative thats subjective . I am @ about 670hp shifting @ 6500 (11.0:1). I know my RB stock block gave up at about 620HP shifting @ 6000 after about 18 months of daily driving and regular racing .
Hope that sort of helps .

Tex