Tire Wheel Fittment questions, 74 Super

[Mister 4]

Hello everyone, just doing some early planning in my head, I have been searching and calculating lately, but right now I am looking at a set of rims. They are 17x7 with an et38, with an option to go to an et48 but in 17x7.5. I plan on getting Topline Maxx Struts on front and convert to all disc brakes from topline also. Along with that, I plan on getting Creative Car Crafts 1 1/4 inch wider rear fenders. So far I found out that having a 17x7 rim with an et55 or 50 is preferable with spacers involved. But so far it seems to me that the rims with an et38 does not seem to add up to me. So I was just wondering if you guys have any ideas or concerns on this?