1st Toyota all the way!!!!!!!!!!!!!

I have a '86 Toyota 2wd that I just recently swap from the 390 3rd member to a 438. My speedometer is all jacked up. I've called the local Parts store and Toyota dealers and they are giving me the freaked run around. So I figure I ask my fellow Toyota peeps. My stock tires are 185/15/60. My summer wheels are 225/18/45. From my understanding I just need to change the speedo gear from the tranny side and should be good. Any help or even part #s to get is greatly appreciated.

Thanks!!

Jorge