Ordered new wheels and I think I screwed up

[donthekawguy]

I ordered a set of 15x10 ralleys with 5 inch backspace for the rear. Will these fit? I think I need a 4 inch backspace. The wheel well lips are already cut out and when I have the wells replaced I will have the rolled so the outside shouldn't be a problem. I'm wondering if I will need spacers or if they will work without spacers.

[PGSigns]

I have 15X8 rally's on my 66 with 265 tires and have about 1 1/2 on the inside and about an inch on the outside tot he bed side. The lip is not even close to the tires on my truck. I is lowered 5 inches in the back. They have a 4" back spacing so nor sure if 6" to the outside will even make it under the truck. I know from my 65 that 5 1/2 back spacing with a 305 tire needs wheel wells widened about 2" on a fleet side.
Jimmy

[donthekawguy]

I just went out and measured and it looks like I have about 1/2 of room on the outside with the lip cut off. I won't be sure until I get the axles swapped out for 5 lug and everything set. I guess I will keep my junkyard wheels and tires till it gets set up. lol