I would like to convert my Marlin 336 from a pistol grip rear stock to a straight grip rear stock. Will a finger lever and bottom tang from a Marlin 1895 work on a 336?

yes, the action is the same.

Yes, but the lever is different as I pointed out; it is cut out for the 45-70, but I think it will still work. Another thing; the lower tangs are not bent; they are solid, so I have milled them flat; that way you do not need to buy one. And I have also hearted and bent the levers into a flat, square shape too; no new parts needed.

Dang, you do a lot of work. If you don't mind spending some money, it is pretty easy to change tangs, levers and the stock.

You will have to heat and bend the existing tang or buy a replacement..Id suggest you sell the present Marlin and buy a straight grip rifle, probably a better way to go..????