The SEL chassis is going to be a bit heavier. Also, most SD's had aluminum hood and boot lids.
Should make a good hiway cruiser once it's up to speed. NG in town.

Front engine shock mount on one side (left I think) is on the wrong side of the crossmember for the 617. It will need to be cut and rewelded.
Then there's the glow plug circuit, driveshaft...

Its easier to find a nice SD.