The engine transplant is a toss up. Having done a 60 - HZ transplant & having been a TLC costumer, it's a toss up. TLC does their job very well -when hire them, they do it properly - the first time in my experience.
1HZ transplant: Used engine, imported $4500 including H55 & turbo. Engine #2, $3500 including H55, no turbo. Add about $1500 to my door in fees (2002 prices).
Personal installation: I bogged at the electrical. Thus the process of finding a mechanic that would work on a Toyota Diesel - not easy. Found a great mechanic, paid for the electrical. Then black smoke & overheating. Lots of months, lots of dollars troubleshooting. In the end - bad engine. Lucky me - I have two engines.
Engine #2: pull the head, reman. the head. Rebuild the injection pump. Source a new Safari Turbo Kit. (That vaporized about 2-3 months & another $5,000+-).
Install #2, with new head, new pump, new turbo. Still overheating issues. New Alum. radiator, Toyota Red, Water wetter. Better, but not perfect enough to drive in 100+ with AC, at any speed.
All said and done: Way over $15000 & I still have a HZ/H55 to rebuild & I still have a minor overheating issue to tackle - assuming I still want to go 75mph uphill.
My TLC H55 transmission I purchased: Price on high end of what was available - it showed up on time, was perfect ready to roll for my application & it is still a perfect transmission - just attached to a 2f, sitting in a parking lot in Bend, Oregon right now. That was one of the easiest & best modification purchases I have made - thank you Jonathan.
If I had do-overs available: I'd do the HZ again, but not count on 1 week of down time. I'd rebuild the engine in advance (another $6,000-$8,000 time/materials) and put a fresh motor and drive-train into my 60. That math alone puts the engine easily at $12,000US.
Now the clincher: The 60 at the time was my work truck. I ended up renting an 80 series for $1/mile for 3,000 miles & driving a stock 60 series project for another year until I got the HZt60 to a point where it could be counted on.
It's a toss up between time & money & ability & tools & space. And to think, I did all this when the exchange rate was in USA favor and the price of diesel was less than gasoline.
Don't even try to figure out how many miles I'd have to put on to get close to break even - it's probably not in my life time.
The HZ did change things from 10mpg no matter what I did - floored most of time to: 17mpg no matter what I do (I don't drive for economy & have a giant Maggiolina on top) & I actually need to lighten the right foot sometimes - imagine that
; plus a verified front end wheelie on Moab Rim; and this vehicle is still computer free.
Enjoy, there are many different opinions, but in the end we all love our hobby/work/play. Bob