Timing Curve on 360 in an RV

You ought to look up the factory advance, which is usually in the servvice manual.
The service manual will also have the initial timing and rpm it is to be set at.
All that initial advance is fine for engines that have slow flame and/or heavy exhaust dilution at idle.
I seriously doubt an RV engine would be set upo that way.

Yes some modifications were made for emissions, and they were altered over the years. So (a) I'm not going to guess what was done for a '78 RV. Find the specs and we can take an educated guess (b) the general chararacteristic of the advances didn't alter that much. All Chrysler engines used a 'two stage' advance in the era we're discussing.