I would actually use the 191/810 heads in your case. They are the HD TBI 350 heads, they are a swirl port design BUT have intake valve rotators and sodium filled exhaust valves for longer life. IIRC, the exhaust seats are a different material too. They will run practically forever in the P-series step vans and school buses they were put into.
The 083 TPI castings will not make the same low-mid range torque that the TBI heads will, FACT. I don't care what the guys on Thirdgen.org had to say about it. I have run both sets on a 350, and also run 187 305 TBI heads and 081 TPI 305 heads on the same 305. In both cases the TBI heads made more HP and torque under 4,500 rpm with the mild cams.
The 1983 cam is the same unit that came in the TBI trucks. Be sure to measure the valve lift of the cam while you have the intake off and everything apart. Cams in the early 80s were notorious for going flat.
Your best gains by far will be long-tube headers with 1 1/2" primaries with 2 1/2-3" collectors. Then use a low-restriction 2-1 exhaust system, exiting into a single 3". This will be a quieter setup for the heavy motorhome that will boost the torque output, right were you need it, down low.
Keep the stock TBI intake manifold, it works VERY well under 4,500 rpm compare to the aftermarket alternatives.
Then my engine build from a couple of years ago.
Install some Vortecs with some exhaust porting and a Mellings MTC1 or Federal Mogul CS1014R camshaft and it will feel like you have 2 1983 350s under the hood, I promise you. The vortecs are lean fast burn heads which happen to flow very well.