help with slow 496!!

i need some input from a big block guy..
engine:
496
srp pistons 18cc dome
calculated SCR at 10.3-1
calculated DCR 7.8-1
Actual cranking compression 160#
Merlin heads not sure of actual runner size, bought em used, was told there were 310cc, machine shop reworked them, said they were marine heads.. i thought no biggie, turns out it could be 320-345cc.
2.19/1.88s
Cam is herbert solid roller
.685/685
253/266 @ .050
108 LSA
102 ICL (was degreed)
Vic jr 4150 intake
Quik Fuel 850 Mech. secondaries.
msd dist.
6al w/ blaster 2
2" primary headers shorties is all i can fit in car

I am worried nuts about only having 160# of cranking compression.. from what I've been told good street engines on 93 oct should be in the 190-200 zone.
Im expiriencing a stumble from idle to WOT.. its mostly when the secondaries come in, Im guessing from a Vacuum drop..
timing issues im having.. I've set the timing at 18* intial, and 36* total, and the Idle to WOT bog is terrible, the best i can clean it up is by the lightest curve springs and setting the timing to a total of 39* it basically full in at 1800 rpm and runs its best, any clue as to why it loves timing? Im guess the low crankning compression..
my next question
I have a fresh set of 781s, light bowl work, 2.25/1.88s
they CC at 121 average. that will lower my compression, the merlins CC'd 116. would I be better off the angle mill the 781's to 110 cc, or stick with the merlins and go with a cam with a wider lsa and lower dur to increase my cyl pressure?

it took 3 years of saving $$$ and collecting parts, and I've ended up with a boat anchor. Im just trying to get my 3550# transam to run 11.00s, im bench racing at the moment because all drag strips are closed for the winter around here..

i do not think you have 345 heads they have a 2.250 or 2.300 intake valves . the heads under the valve cover are mark for runner size and stamp on the side of the head as well .did you O deck the block? i think your cam s to big for your ch you did not say what stall you have ? a heavy car would need some stall and gear with this cam and cr to get out of it way .you could go to a 112 lsa like 621/621 .. 246/254 @050 on much smaller cam but should work better i have had the same build up with more CR and some other things i do .that car was a3800+ car running 11.00

the converter is an allstar performance stall speed supposed to be 3500+
car weighs 3550 w/ me in it..
whats considered a good cyl pressure?
pistons are .005 in the hole