Gonna be something you will have to play with. The problem with stock stuff is when you get enough initial, you will have too much total. You need a way to limit mechanical advance, like weldin up the advance slots. With a truck pullin something you might start with 12-14 initial and see where total ends up. It's not uncommon for total plus vacuum to be in the 60 degree range on a stock low compression motor......BUT whether or not the engine will take it pullin heavy stuff will have to be seen.