Driveshaft Math, Someone Double Check Me?

[toofun]

I have a tko 600. According to classic chevy 5 speed the tip of the rubber boot is 3/8's past the start of the tail shaft spline. My current driveshaft yoke sits about 1 1/4 inches TO THE RUBBER BOOT. Which if my math is correct would put it at 1 5/8's from the tail shaft (1 1/4+ 3/8's= 1 5/8's) I would like to end up with 3/4 of an inch from the yoke to the beginning of the tail shaft.

My measurement of my current driveshaft from center line to center line is 47 inches. So if I am looking to get a FINAL clearance of 3/4 of an inch would that mean that I would need to LENGTHEN the driveshaft to 47 7/8's FROM CENTER LINE TO CENTER LINE??

I am pretty sure I did the math right but if someone can double check it for me I would appreciate it!!

Thanks
Mark
TOOFUN