One of the main things you need to do to help this motor run excellent is to make sure the cam is degreed into 3 to 6 degrees advanced on the intake lobe centers
Your roller cam specs. are close to the same cam in the first pump gas stroker street motor I made for myself, it was 260@.050 on the intakes and 266@.050 on the exhaust lobes, ground on 108 LSA. I installed it at 106 intake lobe center (2 degrees advance) so it wouldn't spin the tires as easy as if I had installed it at 4 to 6 degrees advanced. That motor made me very happy and far exceeded my expectations
It was a 4.250 stroke in a 400 block with 4.375 bore to start with, it had a set of ported big valve 906 heads which got replaced later with a set of CNC ported Eddy RPM. The head change pick that car up right at .2 ET and a full 3 mph in the 1/4, 10.49 at 126 + MPH on Oregon pump 91 octane pump swill through the full exhaust and with the six pak air cleaner on the low deck six intake and 440 carbs.
I change the crankshaft to a 4.300 stroke to move the pistons up from -.025 in the hole to zero deck to raise the compression ratio from 9.25 to 1 to 10.3 to 1, that picked the car up some more also
On the valve spring pressures run what the cam calls for On a solid roller cam 30 lbs. more than needed is way better than 5 lbs. to little You need to look at the coil bind on the valve springs at full open at the retainer, check that with checking springs at the retainers before setting the real springs up and shoot for .055 to .090 from coil bind on all 16 springs
On your deal I would make sure what the end compression ratio ends up at and if it is below 11.00 to 1 I would look at running 91 or the highest octane non ethanol pump swill you can buy and try that first before running race gas on the street
IHTHs
Ain't motor building and racing fun
Do it right once or do it over later