[Donna]

My Newell has a Ford 391 industrial engine, is this a direct derivative of the 390 ? 
Because they have very little information here ( Netherlands ) about the 391, but they do about the 390.

I also want to install a HEI ignition, do I have to assume a 390, will this also fit?
Thanks.

[Latitude 28]

Donna,
Take a look at this Ford Truck Enthusiist forum about your HEI swap.....https://www.ford-trucks.com/forums/1595427-76-361-distributor-swap.html. Digging into their forum found some interesting facts about the 391 industrial engine.

[Latitude 28]

Here are those interesting facts about the 391 I was speaking of......https://www.ford-trucks.com/forums/1379039-identifying-a-ford-361-391ft-engine-and-specifications.html