Have some questions.

I am currently working on a 1973 Dodge Dart Swinger. I have replaced the 318/904/7.25 with a 360/727/8.75 combo. This car is really for my enjoyment, not for big shows or drag. Basically just street driving and an occasional country drive; I live by a mountain so I would have to drive over the mountain to take it to work or to my car clubs cruise.
Here are my current specs:
’87 360 block bored +.030 / SpeedPro Hyp. Pistons (Internal Balanced)
9.5 CR
MPP 340 cam (268/276 adv 228/[email protected] 44 Olap 114 c-line .429/.444 lift)
Magnum head - stock valves (retrofitted on LA block)
Prof. Products Crosswind Intake
3” K&N
727 Trans w/518 pan/TransGo TF-2 Shift Kit/3.2 KD lever/B&M flex plate
8-3/4 rear / SureGrip / 3.73 gears / green bearings. 205/60R15 tires
Summit universal alum radiator with separate B&M trans. cooler
I’m planning on a TTI 2-1/2” dual exhaust and headers with an X-pipe and Flowmaster mufflers; an MSD 6A ignition module, and Royal Purple fluids throughout.

My questions are:
1.Which Holley Street Avenger carb should I use, the 670 or 770 CFM?
2. Which stall converter should I use? TCI suggested a 1600-1800 stall, I’ve been told that’s low.
3. Because of the X-pipe characteristics, which Flowmaster would give me the same sound range as
my stock 02 Dodge Ram, the 40 Delta or the 50 Delta Flow mufflers. Flowmaster techs won’t
give me an answer except that they offer a variety of mufflers. I don’t want an over aggressive
sound.
4. How much horsepower do you feel I could get with this combo using pump gas?
5. If I go with the MSD box can I still use my stock distributor or do I need to go with an MSD?

The engine/trans/rear is finished, so I’m not looking to replace anything. Thanks for your input guys.