Having been a QM for a while I have tried to fight a way through this minefield for the past eighteen months or so. By no means am I an expert but I gladly pass on to you how I have tried to interpret this issue and work it into the 145 for the benefit of us LAE's.
A couple more thoughts KP, 66 is basically designed to encompass the A & C disciplines into one combined licence, a bit like the poor old chopper blokes have always had to put up with. A type rating is only issued on 66 as a combined Airframe and Engine. The problem is this also extends down to the basic 66 B1 ratings, as you are no doubt aware. Because your present coverage is limited to LWTR A2, upon conversion you will pick up some restrictions unless you have the modules in your pocket we have already mentioned.
I think it would be very difficult, at this time, for your QM to issue you with a full A & C authorisation. That said you should be able to automatically qualify for the 66 A category privileges.
Its probably best that you consider persuing the missing modules over the next months and then convert to 66 B1-1 and deal with the restrictions , if any. If you do not have any existing CRS privileges above Limited and Simple ( terrible term, no slur intended sir ) and no protected rights issues, based on the fact that your LWTR A2 is young and as you correctly say the LWTR C road is gone there is not much for you to gain by not converting.
Have a chat with your QM, he/she will know your MOE and may be able to come up with some options. We have just dealt with a couple of situations like yours and in both cases we had to convert, best for the individual in the long run. Believe me it was a last resort, our MOE is nothing if not creative.
In short mate you need to be A & C now! Sorry if this rambles but its difficult to explain a 3 dimensional problem in single dimensional terms. Again good luck.