Hi, ahh the front frame
its a tricky little blighter
if you make the jig as per book it,ll come together if you take your time it.
before you fully weld it, just tack it together & offer it up to the build table & check the dimensions as per the book.
it took me 2 attempts to get it right
i,m fairly local to you so if i can help then just shout.
andy