Early A 273 manifold - flange pipe questions

I'm at the point of trying to get an exhaust system for the shop car - keyword: inexpensive! we are out of money!

Car: 65 Barracuda w/Rebuilt 318 +.020, Summit 6901 cam, Eddy 1406 and performer intake. 904 / 8.750-3.91SG
Staying with the OEM 273 V8 manifolds. Just a street car, built from what we could find. Not a race car. Just looking for weekend fun and some good noise!

I'm thinking of running 2" (OD) front to rear as true duals (no X or H pipe) with cherry bomb glass-packs. Trans cross member modified for duals.

Questions:

1) What is the ID of the stock manifold outlets?
2) Should I run 2" or the stock size? (I assume 1 7/8 is stock)
3) What is the bolt pattern? and where can I buy GOOD thick flanges (muffle shop said to get them first)
4) Muffler shop said "~$400" to fab and install pipes using my glass packs. sound about right for east coast prices?
5) Any cheaper way to go??? what are the chances of finding a good used system?

Pics of what we're working with:

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