Yes, you can simply modify OEM 700R4 Dispticks by bending them carefully either with a plumbers pipe bender or over something round with beveled edges to follow the contour of the trans tunnel. It just takes 2-3 minor bends.
Note: use a dipstick from a passenger car - the ones from the vans are too long!
I do not know if these numbers are still available, but they worked great on my 66. GM 10085252 for the dipstick and 7501191 for the tube. I believe these were from late Camaros with the 700. Have your GM parts guy confirm the numbers are right.