wheel questions

[61_FL_Apache]

A friend of mine gave me this set of 15X8 chrome rims.. They are in pretty good shape and plan to use them for now.

First question: The bolt pattern is correct for my truck, however, the center hole is larger then my axle/hubs and old wheels. See pics below.





I have these on the rear right now and see no issue with running them this way, but not sure if Im overlooking something.

Second question: These wheels had a center smooth cap at one time. I have similar rally wheels on my Tahoe and the center caps almost fit the wheels on my 61. Is there these caps are measured for a replacement? They have 3 small nubs that hold the caps on.

Thanks for your help!!