I just got my rebuilt motor running and I have some questions about the timing and carb. My motor goes as follows...

355 sbc
flat tops (about 10:1)
edelbrock performer RPM aluminum heads
Lunati cam 227/234 duration at .050 490/504 lift, 110 lobe seperation
magnum rockers
stays at about 185-190 degrees temp wise.
750 holley, vacume
Accel distributor

My first question is when I went to set the initial timing I took the vacume line off the distributor and set it to about 10 degrees advanced. I hooked the vacume back up and it went up to about 18 still at idle. Is this right?? I dont know if its supposed to advance right off idle that much?? Also for my set up what do you guys recommend for total all in timing?... When I nail the throttle it hesitates first then revs up. A 750 is to big for my set up correct? Will a smaller carb make it more snappy? I will do ANYTHING you guys tell me to, to make this run a little better and get it figured out. Thanks for the help