final drive

[rovermike2011]

I be entered the CRX in bishop court in September
she be 1800 type'r n/a but i need advice on which final drive to use
do i use the original 4.2 lsd cable which has long fd or 4.4 or 4.7 which has short fd or use 4th and 5th out of the 4.4 in the 4.7
or can i take gears out of different cable gearboxes
and put them into the 4.2 box. i am try to figure out which be the
best fd and gear ratio to use.
i known Paul and Steve done drag racing
any advice or info would be greatfull