I would not call it a "Transitional Model A." To the untrained eye, it looks just like any other 28 or 29 Model A. The biggest giveaway is that the emergency brake is on the left hand side of the steering wheel rather than in the middle. There are hundreds of other differences, but if you want a quick way to figure out if yours is an early A, that, in my opinion, is the quickest way. I could not quickly find a list of the early features, but there is a Facebook page for Early 28 and Fine Point, although that site has a lot of other stuff on it.
https://www.facebook.com/groups/E28Modelaford/ The MAFACA site also has some photos of 28s.
https://mafca.com/gallery_1928.html
The definitive way to identify the early cars is by the serial number on the engine and the frame. Others who are more knowledgeable than I can provide the cutoff date for most early features, which you can compare to your engine and frame number.
http://www.fordgarage.com/pages/ABenginenumbers.htm As yours is cut down, the engine and frame may not match. Here is another link that might be useful.
https://www.mafca.com/whatyear.html
Many others on this site are expert at this. I am not, but I thought I would at least give you a place to start. Photos will help immensely.