You need to make sure you get the right fitting. Spindle size varies depending on which year/model monster you have. I've got a forged PVM 10 Y-spoke on the front of the trike - a nice looking wheel but they are expensive. I went for the PVM as it matched the 17" rims I opted for on the back.
I got my front from Harris Performance - cost just under £500 (ouch)
https://www.harris-performance.com/w.../frameset2.htm http://www.pvm.de/w/d/mo/products/neue/liste.htm