Having had a good amount of suggestions and ideas about making tapers I figured I'd show the results.
I made it to our metal salvage yard a couple of days ago and found some rusty (but good) steel round bar stock. Not sure what it is but it isn't easy to get a really good finish on it even after removing all the rust. The OD was just over 1.4 in. so great for my MT4 project. The compound on my lathe will give almost 3 in. of travel if light cuts are made.
An MT4 centre was held between the chuck (point into a divot on a piece of stock held there) and a live centre in the tailstock and a DTI was used to adjust the angle of the compound (as per earlier threads). Once the compound was set, the bar stock was placed in the 3 jaw chuck and turned down to about 1.24 in. Diameter (the diameter of the female MT4 spindle at the large end). Once this was done the compound was used with a carbide insert to turn it down close to the finished size. A sharp HSS tool was used for the final cuts.
Leaving the new taper in the chuck, the chuck was removed and the fit tried using some blue artist oil paint (my only MT4 female fitting is the lathe spindle). It seemed to be a tiny bit bigger on the large end but there was some transfer at the tail end and it locked nicely in place so I decided to leave it. It was gone over gently with a lathe file and left. The tail end was drilled and tapped 3/8 - 16 as that is the thread used on some other similar pieces I have.
The final test was to remove it from the chuck and install it in the spindle to clean up the portion ahead of the taper and give it a final facing. It held nicely for some moderate cuts even without a drawbar - I didn't have one made at the time. I realize there is some risk of having it turn in the spindle however it was nicely locked in place with just a gentle tap of the hand. It will not come loose without being tapped firmly from the back.
A photo of a commercial MT4 dead centre along with the newly minted MT4 taper:
Photo of a newly made rest for wood turning (smaller items) along with the MT4 taper. The front end of the taper will be drilled out for a pen turning mandrel - I'm not comfortable using a chuck to hold the mandrel as it brings my left arm quite close to the chuck jaws:
Another view of the rest showing the adjustment bolt with brass insert (to prevent galling of the inner post). The collar at the top of the post was pressed in place (the hammer method) with a bit of locktight for extra insurance - it won't come off. My brother was kind enough to weld the post to the plate - too bad he doesn't live closer as he has some great welding toys:
I realize that references to turning wood on my lathe will make some of you shudder however I just do not have room in my shop for other tools (although I might just find a corner for a shaper if I ever came across one). Once suitable paint is located the rest will be covered.
Thanks again to everyone for the help regarding taper turning.