the 3.03 3 Spd is virtually unbreakable behind the 200 and a considerable upgrade to the 'Peanut' 2.77 non syncro 1st - 3 spd.
.
66 200 block
should be 'dual drilled' for early small BH standard/2 spd Slushomatic tranny AND the larger BH, Clutch and flat faced FW.
.
You can verify larger BH bolt pattern by looking at rear of engine. The small pattern auto/std BH is
below top of block-cyl head line and the large pattern will have the top two bolt holes visible with the 2.77 BH. The later Toploader BH is flush to top of block at the cyl head line.
.
'Dual Pattern block.

.
Early small pattern block has BH @ 2" below cyl head :

.
later 'dual pattern' block with 3.03 toploader is flush with top of block where meets cyl head.

.
The C7ZA 3.03 Toploader Bellhouse is maybe most common and somewhat available. This one was on a 1971 Maverick 170. The larger flat faced Toploader Flywheel is also needed for the swap.

..
the 2.77 uses the tiny 1100 series output yoke and rear universals with smaller tranny output shaft (25 spline ?). The toploader has the larger (28 spline ?) output shaft and typically has the lager 1300 series universals. Swapping from the 2.77 to 3.03 will need the DS 'retubed' with correct ends OR there is a larger 3.03 output yoke with small 1100 universals available from "Modern Drive Line". The
length of DS needed is a question until swap is completed.

.
The original '66 pedal clutch linkage can be used on the 3.03 BH with minor mod to original Z-bar to TO arm pushrod pivot location on the Z bar.
.
Maverick 3.03 swap on my '61 used original clutch pedal linkage and the 3 on the column shifter from the 2.77.
.
... when you're all done you will may be very happy with Toploader and later diaphragm clutch from Fairmont application.
.
have fun