I owe you a huge apology for not responding to your question. It got totally lost in my notification box. Sorry about that. If you are still looking at using a twin I beam front end, I found that making the frame rails 32" wide (measured outside to outside) works well and then plac3 the axle pivot mount holes directly over the frame rail. (works on axles up to 79, later axles require different mounting positions). Hope that helps a bit. Again, sorry for the delay.
are there any standard measurements I should follow on the frame build . and is there any measurements when some one uses the twin I beam type front end . I did not no if the book shows dimision on it .