Nice work so far wokka. For the swing arm, why not just cut off the stock side rails on the swing arm, re-weld in some longer ones ....reusing the stock top pivot tube and axle plates, welded back on. You could also weld in a cross brace , up near and behind the pivot tube to stiffen things up...... or for something stronger, an arch shaped gusset made out of 1/4" plate, welded in. The round Tubed swing may look better the Boxed?
A 170 tire on the back? WOW ! Maybe a bit much for this little mill.
Thanks mate, I must admit, I'm having a blast
To be honest, a cut and shut on the side rails was my first thought, but there's a couple of problems
1) Because of the angle the 2 side rails are in relation to the pivot tube, to do it right, I would need to put a bend in them to get the width for the tyre, even with a 4" stretch
2) Putting a bend in round pipe, and then lining everything up is a ballache, been there, done that, bought the t-shirt
3) If I go pipe, it rules out the jack shaft option (on my skill set anyway)
4) A good heavy wall box is easy to work with and get everything squared off and braced