I have installed this kit from
www.4wd.com and it worked great. I know my way around a 258 pretty well but am no mr. mechanic and it was a 2-3 day job at a very relaxed pace. Only problem encountered was the factory wiring on the pump was backwards. Fixed it and it fired right up! Noticed increased fuel economy (about 3-5 MPG extra.) Did not notice a power increase but that 258 was VERY tired and in now in the process of getting a new heart. I put the TBI on the rebuilt engine last night on the engine stand and hope to put it in the Jeep this weekend after the HEI upgrade goes on. After all this I am hoping for a really sweet running 258.
In my opinion I would do the HEI retro first and then move on to the TBI if the first doesn't achieve what you want. Everybody loves the HEI retro and I have to find out for myself, but I already threw the $1000 at it for the TBI retro. Just that really gave it life in the cold Wisconsin winters.
'79 CJ7, '83 CJ7, '84 CJ7
258s - 1 w/ Weber, 1 - w/ Howell TBI, 1 - in restoration