If I were you I'd baby that motor and start saving for a rebuild. I really wouldn't worry about cleaning it out. If it's smoking the motor really needs a rebuild. I wouldn't seafoam it it'll speed up the death of the engine at this point. You'll have trouble with oil leaks and more smoke. Do a compression test. If it's high then seafoam it. If it's low start planning the new engine. The engine was mistreated in the past. It'll probably last a few more years if you just take it easy with the revs and just change the oil every 3 months or 3000 mi.
89' YJ Larado 4.0L,AX15
05' Grand Cherokee Limited, 2"OME lift and a Hemi.