i have been told, and it is my experice that the seam allows is to be the same. I use my foot of the same machine.. I do have 3 machines. all differant generations of sewing.
1 Marsh Brady style clothes
2 baby clothes and quilts 1980s
3 now.
Good luck. try this hint. also, as you layout.. take a picture of your arrangement. .the wonderful age of digital !
Ellen