After further thought and calculations, it would appear the the figures prefixed with "-" i.e. a negative sign, should be taken as indicating in effect ATDC, not BTDC. If this, as well as point contact measurement is accepted, things fall more or less into place. Please read this in conjuction with my previous posts.
One can of worms, to be sorted out only by means of actual readings in respect of the modified cams. These figures I await with great interest.