Seems like the T50 bottom-bracket is lower than it's seat pan, while the V20 BB is typically higher than the seat pan. To replicate the V20 riding position you might remove the T50's rear wheel, lower the rear of the bike, and figure a way to support it at the proper height. Then perhaps rig a V20 seat onto the T50 frame.
If mounting on an indoor trainer, where weight shift to the rear does not matter, then you could also move the seat base rearward, rotate the BB upwards and rearward to keep the same distance from the seat back and base to the BB as before.
Lower the seat back to 21 degrees. The rear clamping stays might need to be shortened!
You might need a 451 (22") or a 406 (20") rear wheel to allow for the 21 deg seat back, and pack the wheel up!
You would also have to reverse and lower, the steerer stem, and possibly buy a new one of different length, so the hand position is the same as on the Vee!