A few Questions

[glock35ipsc]

It's possible that a good TIG welder could modify your tank by welding in a bung that would accept a factory-type sending unit. The biggest problem though might be the depth of the tank -vs- the depth of the sending unit. There might not be enough depth to shorten the sending unit and still have room for the pump and float assembly itself. If you have the ground clearance, and need the extra depth, a sump could be added to the bottom of the tank for the pump to sit down in. That would also help with hard stops and cornering when the fuel level is low too.

If you end up using a factory type pump, the ACDelco EP381 is the perfect pump for this swap. Factory, off the shelf availability at any parts house, and costs less than $70.