Well I may play with it Joe, but it turns out the bore I'm working with is much larger than the molds I have. Today I cast up slugs from numerous old Ideal mold blocks, and when I finished I checked diameters on all. They all fell down the bore with no resistance. They will need a significant amount of lapping to get from the .311" bullet to the .318" bore. 
I've decided to just table the idea for now, and instead get a mold built that will drop a .319" bullet. I have some cast bullets here that are .320", but from what I can tell, they wont breech seat very easy, as they're harder lead alloy, and not stepped like I'd prefer. Would really like to have light engraving on the forward bands, and the .319" base band. Maybe a .316" first band, and then .317" or .318" 2nd and 3rd bands.
Since this gun has a very slow 1:20 twist rate, I hope it will stabilize a 150 grain bullet. I'm pretty sure the heavier 170 and 180 I have are too long for the 1:20" twist rate.

Shockingly simple! Yes, I agree. 

        Joe.

Vall,
This bullet may work well for your application. They're not to hard to find on Ebay

The dimensions are taken from my mold, using 20/1. It's made for the Win 32 SL. I got it to use in a Douglas .321, 20 twist barrel.

In 30/1 it should should be slightly smaller and BS fairly easy.

Frank

My reamer only cost $8 and I can use it over on another mold, if need be, thank you.

No matter what you do you need hard wood shims like tongue depressors or popsicle sticks. The wood shims allow the mold blocks some misalignment and allow them to be tilted if necessary when you tap on the blocks with a urethane hammer.  This permits the mold cavity to dialed in with a dial test indicator. The outside surface of the mold block is not really functional but the cavity has to be dialed in dead on with at least a .0005 indicator. If there is misalignment in the blocks that affects the cavity the indicator will tell you and you can do more adjusting. 
With Lyman molds many of the cavities are not round from the factory. They tend to be egg shaped. When you find that you have to dial in the opposite faces of the mold to give the same number then bore the base band round. 
You may find yourself salvaging a mold that was nearly junk when new. Then you have to exercise some patience to center the mold even if the blocks were offset when originally machined by Lyman.

frnkeore wrote on Sep 27^th, 2015 at 3:50pm:

Some of the best molds I have are recut molds.  I even have one you modified, Frank.  Many mold makers recut old molds. 

If mold blocks don't line up, can be machined or surface ground before mounting in a four jaw chuck. I use quarter inch thick brass shims to hold the blacks together in the chuck. The other two jaws touch the mold lightly. Ron Long used a two jaw chuck when boring bullet molds.

Reboring an existing mold just a few thousandths of an inch is near impossible. 

          Joe. 

Think I have been here before, but these "Z" shims hold molds nicely and only have to clamp in a 4-jaw just enough to hold in place. Front lip rests on chuck jaws
Chuck

Did you check out Hollow Point Mould Service, one of thier specials is reworking drive bands? Looks like the biggest charge is chucking up the mould.