Little help here, please (part one of 2)

[King Scooter]

Looking for some advice on how to finish up my carb mods and rebuild. It’s a long (2 part) post but I want to get all the info out there for the gurus. I sent this same info to Cliff's "Request a quote" messenger but haven't heard anything back yet, so thought maybe this it the proper place to post

I've purchased a SR kit from Cliff including a choke pull off, electric choke, idle tubes, SMR, PMR, brass screw in restrictors for MAB (upper and lower) and DCR, etc.

I'm following Cliff's book and doing all the modifications and suggestions including throttle shaft bushings, 90d primary & secondary openings, air flap adjustment screw. I'm restricting the original large MAB and I notched the air flaps at the fuel holes.

Here are my car and engine specs:
1972 Monte Carlo with power brakes and A/C. My long distance cruiser and spirited driver.
Engine:  350 ci SBC, 1 pc rear main seal, roller block,  9.6:1 CR (measured), zero decked with .039 head gasket for .040” quench, oem 11cc dished pistons
Heads:  Vortec heads (actually Engine Quest vortec replicas), milled to 63 cc chambers, 170 cc intake port, screw in studs, beehive springs @ 95# seat, 150# open, Stainless steel 1.94” int, 1.50 ex valves. Harland Sharp .080” back spaced roller rockers and proper length pushrods for geometry
Cam:  Straub Technologies semi-custom hydraulic roller. .510/.468 lift, 221/227 @ .050, 109d LS, 105d ICL
Exhaust:  1-5/8” long tube headers with 2-1/2” mandrel bent full exhaust with Pypes Race Pro turbo type mufflers, bumper exit. No X or H
Intake:  GM Bow tie, aluminum, dual plane, spread bore, vortec style
Rear end:  3.31 gears with 26.6” tall tires
Transmission:  Art Carr/CPT 200-4r with 2200-2400 stall and no lock up converter
Distributor:  GM points type, vacuum advance distributor with Pertronix ignition module
Timing:  17d initial at 800 rpm, 34d total at 2850. Vacuum advance limited to 10d all in at idle. Cliff feels I may have too much final so I will work with this
Vacuum: 14.5” at 850 rpm idle, 12” at 700 rpm curb. 14” - 15” at no load cruise 2000 rpm, 13” at lite load/uphill 2200-2300 rpm
Continued…

[77cruiser]

Is that what Chris recommended for springs? Seem a little light to me. 130 closed & 320 open I'd think.

[King Scooter]

I can't say that Chris recommended these springs.  They are the GM LS6 beehives that normally get installed on the GM HotCam combination.  I had a brand new set in my inventory and both Chris and Pete (CPMotorworks) who did my heads, said they should be fine for what I was trying to accomplish.
Not looking to set the world on fire, just wanted a good running, efficient but aggressive cruiser. Max RPM under 6000 rpm. BUT...the engine does begin to cut btwn 5700 & 5800.

Could be any of these things that I haven't begun to chase down yet...1. Soft springs, as you mention. 2. Pertronix not happy above 5800.  3. The rev limiter dial on my Pertronix, set at 6000, isn't really 6000. 4. OEM tach isn't accurate.
Once I get the car back on the road, I'll be looking into this.