You said you wanted a good idle and be able to travel a lot on the highway. I wouldn't go overboard on the cam.
Seems people forget they get higher horsepower with bigger cams at the high rpm limit of their engine. Unless you're racing you won't be spending a lot of time at 6,000 rpm
You need a cam that will give you good low end torque, good idle and good street manners, from the way you described your intentions with the car, a mild camshaft would give you that. I wanted the same when I built mine so I got a rather mild [for my build] cam. I have all the torque I need for climbing long hills on the highway and still plenty of power when I need it. I'm quite sure I could get another 50 HP out of this engine with a simple cam swap but I would sacrifice some of the low end torque and the 50 HP would be above 5,500rpm.
As far as a roller cam, I lean towards them. Not for extra power that can come with an aggressive grind but for insurance against a flat tappet cam losing a lobe or more during break in. There has been a lot of new builds losing the camshafts during or right after break in. Some people blame the camshaft manufacturers and some the lack of good oil. When the oil manufacturers cut down on the additives a rash of cam failures followed. Proper break in with break in oil should alleviate this but it still happens. The roller cost a lot more than a flat tappet but pulling the engine and making repairs after a cam failure costs more. If you do go for a flat tappet set up make sure you use a lot of assembly lube and strictly follow the proper break in procedures.
I agree with Oldskool, the Melling standard Pontiac pump is my choice. While mine was on the dyno it stayed at 65psi all the way from off idle to 6000 rpm.
My opinion anyway.