one piece floor pan 1961

[62c30]

I am planning on starting on my grandfathers truck hopefully around the first of summer. The truck is pretty rough and there are several holes in the floor. I am thinking it might be easier and cleaner finished product to use a one piece floor. Issue is the frame is rusted out, I have a 63-66 frame and I am getting another 60-62 frame in the next week. Not sure which direction we are going with the truck yet, stock or not. If i decide to "hotrod" the truck and make it a driver I'll probably use the 63-66 frame. I know the cab mounting is different so my question is can I use a 63-66 one piece floor on my 61 to make it easier to bolt the cab to the frame? Thanks