"There has been much discussion
on the usefulness of the brake servos. Do you know why the servos were
discontinued and do you have any opinion of their effectiveness?"
WATCHPOINT: These early Girling servos are unrelated to the later POWERSTOP servos used on all Classic Morgans after June 1993.
Secondly, what is the procedure and advantages of converting early Morgans from front drum brakes to front disc brakes?
The brake servos were very effective; I believe they may have been discontinued because of European legislation requiring a mechanical linkage between the servo and the brake pedal.
On a conversion from front drums to discs, the procedure is to use current 4/4 disc brakes which will require caliper brackets and in some cases new stub axles. The advantages are overwhelming for a car used other than a show car - greatly improved stopping distance and considerably more control under braking (i.e. the elimination of brake "pull" to one side or another).
I think the early Brake Servos were discontinued due to lack of supply (they became an obsolete part due to modern vehicles using a Brake servo/Master cylinder unit as per current Morgans). They were effective but there are now major parts availability problems for the old units.
To convert drum brake cars to discs you need new hubs, carrier bolts, the discs, the calipers, caliper carriers, bolts, flexible brake hoses, and, of course, brake Pads. The advantage is BETTER STOPPING POWER!