Advice: Solid Roller or Hydraulic Roller for street car

well... let's start with what your current set up is.

because slapping a set of zooty heads and a big roller cam into a ho-hum bottom end is a recipe for a blah motor.

"mild 318" could mean a lot of things...

to that end, and with street car in mind, i'd say a set of eddies or something like speedmasters or even some stock heads that have been breathed on a little are a better choice than the trick flows. and considering the targeted mileage, i'd just go for a solid flat tappet. i wouldn't worry about "leaving anything on the table" with a street build, you can get everything you need without going roller.