727 Drive shaft & Ujoint Question

Couple of questions : 1. Is a small block 904 and 727 the same length? 2. Is the transmission yoke the same spine between the 904 and the 727? 3. My new eight and three-quarter center section has the bigger U joint on the U joint carrier, but my driveshaft is sized for the smaller U joint where it connects to the rearend. Is there a joint that has the bigger ends for the eight and three-quarter and the smaller ends for my driveshaft? The driveshaft is from a 904 and 8 1/4 rearend. Thank you in advance for any feedback.