I had my ashcroft flex plate kit sitting around for a long while too.
It was $206 landed and cost me $100 for a used torque converter. 
I got it (box/transfer case and rear mounts) all bolted up friday late at night and had a rest day saturday then finished off late sunday night (starter, cooler lines, prop shafts and cross members).
I've done about 15km since then and as yet noticed no issues re 'bogging down' and definitely do not need a tune, but I am driving sedately not spiritedly, however if you already have a tune I think you will love the extra 'liveliness/push' coming on a bit sooner.
Later today when I get my lazy self moving, I will be fetching a trailer load of sand/metal mix for some concreting so get a better idea of difference under towing load.
Going up our railway overpass on a quick spin around the block sunday night just after assembly I was happy to see the revs under 2k while pulling up the slope at 60km/h.
I actually did an epic write up about 2am monday of my trials and tribulations and successes too and the lappy froze 

  , I was too tired and disappointed to redo it .
I tried to video how to put the torque converter bolts in using just the ratchet spanner (no extra hole in box, I only used pliers for bolts 1 and 2, then clicked how to do it without the pliers) but the phone and my face and obstructed sight line didn't cut it.
Basically I fitted the bolt onto the ratchet end of the spanner then gingerly squeezed in between flywheel and flex plate at 90 degrees (ie bolt parallel to flex plate) then a slow turn placing the bolt into the hole. The bolt is nicely flanged so then applying pressure on the spanner with an extended finger created enough friction for the bolt to sit in place and not turn lefty loosy,allowing the ratchet to ratchet and grab the thread.
It helps to check that the transfer case is actually engaged b4 you (meaning me) assume the torque converter is a dud and have a mini meltdown when you go to move off the ramps!!!
Anyway while I had it up in the air for a few weeks I did absolutely none of the jobs on the todo list, the whole exercise was to get the torque converter in and make it more palatable to drive, as I have never been a fan of slippery converters for daily use and have had an absolute gutfull of the way it came out of the factory, and wasn't prepared to put more time and money in catching up with all the neglect unless it stopped revving and going nowhere while those injectors clatter away maddeningly.
So now much happier and I would suggest to those contemplating this mod to just do it and not be apprehensive of loading the motor down or needing a tune. In fact the only 'loading down' I have noticed is simply the revs are not being silly so it sounds different because the donk is under load and actually using its torque to move the vehicle. 
I am not waxing lyrical over the improvement but it is more than substantial enough (in my never humble opinion) to justify the cost even if you are not good on the tools and have to pay your local indy to do it
Bookmarks