rd or dt? new project need help

[johnnyspencer]

hi all i have just got a new project its a mk1 rd125lc. I have got 2 engines to choose from one is a 12a and the other is a 10v which i think is the unrestricted version of the dt. Can anyone tell me what the difference is between the dt and the rd engines and which 1 will give me the best low to mid range power? Im planning on fitting a lightned flywheel, a reed block spacer, and a micron pipe whichever engine i use. Iv also got some green plastic reeds that im not sure about i have been told that they are boyson racing reeds but i am not sure? heres a pic of the bike as it is now.

[Norbo]

Id stick the Dt bottom end in with the rd top

[johnnyspencer]

im not too bothered about top end speed ,as long as it will do about 70mph. iv had a good look at the 12a engine and its in a bit of a bad way the sump plug threads have gone and the exhaust stud has snapped on the barrel so it looks like ill have to go with the 10v, if its too much on the bottom end power couldnt i just change the size of the sprockets anyway?