Rebuild or Replace 850 TQ for a Mild 340?

A previous owner put a 9009S Thermoquad on my 72 Duster 340. It has sat for years and has not run since I bought. I discovered yesterday that it has the "850" cfm TQ carb, date coded 1975. My question is this; should I rebuild/reuse this carb or get a reman smaller one, like how it came originally? It is a #s matching car that I'm restoring to mostly stock appearing. I'm going to reuse the RV2 ac compressor and it is an automatic w/ power brakes. The engine is going to have 10:1, machined J heads w/ 2.02 valves, a mild cam, and long tube headers. I'm only looking for 300+ hp and the car is going to be used for cruising in traffic. Thanks in advance.