I do not see a major problem with the main tube length, but I do see some major issues with the other criteria listed for jet nozzle sizing and angles. A 5 degree angle is very steep and great operation can be found in the 10deg-15deg range with 11deg being the most utilized. The jet tube has been listed as the same size from 1 1/2 up to 2 1/2, and listed with 4" using a 5/8" feed. While this can be done, it requires running much higher pressure.
Standards for these jet inlet tubes are generally 1 1/2=3/8", 2=1/2", 2 1/2=5/8" 3=3/4" and 4=1". This allows for good operation from a pump running pressure of 30-40psi and delivers more working volume of water jet for each increase in jet size. The pump volumes listed looked ok.
For reference, I have a 2" keene jet that has a 5/8" jet orifice in the inlet tube(yes it is bigger than 1/2"), this jet orifice passes approx. 75gpm at 30psi. For a 5/8" jet orifice to pass 200gpm in a 4" jet, the running pressure (not max pressure of the pump) would need to be approx. 200psi. vs a 1" jet orifice inlet which would pass 200gpm at 45psi.
I would not build to the listed specs in the attachment. Hope this helps
