restore/moding a 74 360, boyesen reeds, bored once over, stock exhaust and airbox. (indiana)   suggestions on what jetting should work?

start at 170 main and needle middle clip, stock pilot. should be close with the stock air filter.

At the risk of stirring up trouble I would like to pose some questions on this.

The 'main jet for the '73 360 is #230. In '74 it changed to #170. The '74 360 has a reputation of burning up pistons. New ones are hard to find.

Has anyone with a '74 360 installed a larger jet? If so how does it run?

Has anyone with a '74 360 burned up a piston?

I had my stock DT360 on a dyno tested at sea level on a 70F day and used an exhaust gas analyzer to graph the air fuel ratio with a 180 main jet, it was too rich with the stock muffler baffle and air filter. removing the baffle and putting a high flow air filter made the 180 main jet OK.
I run a 160 main in my stock bike now for that perfect golden brown spark plug. 170 should be a good place to start if you still have the baffle and Yamaha air filter as far as I can tell. Its nice to not have it too rich at sea level that way when you ride up elevation it handles It Ok without fouling.

The stock jetting is about as good as it gets, which is not great.  These things burn pistons while cruising at part throttle, especially at higher revs.  The detonation is constant and severe if you're trying to run a steady 60+ MPH on a bone stock 74.

You can go through the motor with a fine tooth comb to ensure there are no air leaks, it's always a good idea on a bike of this age.  That didn't resolve the issue for me, nor did a modern carburetor.  You can fatten up the pilot and needle until the bike is miserable to ride and it will still ping.

If I were going back to square one, I would start with re-aiming the transfer ports.  I think that was probably the most effective change when it comes to getting this motor to run properly. 

I have same bike rebuilt to stock with cleaned out exhaust and stock air cleaner with the top of the tool tray cut open for better flow and less noise

I am running 180 main and 55 idle jet with stock needle and needle jet raised up one notch richer.

I am not an expert, but this reduced the off idle surging commonly referred to as 4 stroking

PS - Turbo dan is spot on re air leaks, I would replace crank seals if they are original and pressure test the entire contraption.  I learned the hard way and melted piston when leaks in combination with a 140 main which I didnt double check melted my piston which I had to buy from CMSNL for ~200Euro