[erps]

You can get a standard delco externally regulated alternator for under a $100 that will put out 50 amps or better. You'll need an external regulator which vary in price from $20 for an automotive regulator to a couple hundred for a smart regulator.

 

[erps]

Some engines allow you to bolt on different size pulleys, a small one for your water pump, a big one for your alternator. The pully on our MD17 that runs the primary alternator must be 10 to 12 inches in diameter. Even then, I run the motor at a high rpm when its putting out the amps to reduce belt wear. I don't know how hard it would be to modify your bracket to switch to a small case single foot alternator. Perhaps you could borrow one and see how well it matches up?

 

[erps]

The nomenclature for the small case delco externally regulated alternators is 10DN. I got mine two years ago at an alternator repair shop in Bellingham Washington for $75 IIRC. That did not include the regulator. I just googled Delco 10DN and I don't see any that cheap right now. Here's a hit for $114. An auto wrecking yard would be another source. There were a lot of those alternators built.

https://www.vichubbard.com/auto-part-detail/powermaster-7102.html?js=n