timing/tune up problems

Hey Guys n gals i got a fight on my hands lol jus finished getting my 318 stroker installed and running but i can't seem to dial in the timing or carb tune up

here goes with what i've done

Initial Timing set to 15 degrees

Finial timing is 40 at 4800rpm

ignition is all msd 6al box, blaster IIcoil, and pro-billet distr
is my timing curve too steep for an a-body with a stroker? have stop bushings to limit mech advance at 28, 25, 21 or 18 currently has the 25 installed. or should i install lighter springs to get all-in timing at a lower rpm?

Also once timing has been set i try and tune my edelbrock 1406 carb and turning the mixture screws have lil to no effect on vacuum or rpms, even turned all the way in.
I'm thinking i have too much initial timing causing high vacum and drawing fuel into the carb???

what do ya'll think? where should i start?

also not 100% sure on my advance timing light i left it in the sun the other day and it got very hot and the display flashed when i tried to use it hot but seems to advance and flash properly now

thanks guru's