340 Crankshaft bit the dust

The OP's proposed Eagle crank is going to be difficult to balance with stock rods and pistons, if not almost impossible. It is designed for a target bobweight of 2050 grams as Pishta said. (Numbers are right out of their catalog.) The stock 340 rods and pistons have a bobweight of around 2310 grams. It is going to take a LOT of weight added to any Eagle crank to make it balance out with the stock rods and pistons. It is a 100% non-starter approach in my book.

A stock early 340 crank is going to be stronger and cheaper to use. Shop around $100-150 for a 340 crank is not unusual.

BTW, 2050 grams is a lighter bobweight than any of the stock 340/318/273 setups from the factory by anywhere from 70 to 260 grams. So these Eagle cranks won't balance with any stock LA piston&rod setups without adding weight.