opinions needed i have a 94 Electra glide i have a chance to get a 120" m/p top end for pretty good price used of course but i can clean it up i know i have to cut the cases for cylinders but wondering about balancing fly wheels and what else im going to get into so far its a stock motor with ev 27 cam and dyna 200 i ignition

 

You really need to give us more details of the parts you are talking about! A stock Evo cannot be made as big as 120", the parts are simply not available to do that. The crankcases cannot be bored by very much, as a twincam can, for example, so increased bore size is very limited. With increased stroke in stock cases it is possible to get a little over 100", but the cases really are not man enough.

Just what is this '120" m/p' top end and what has it come off?

 

I believe that the internals from a Merch 120" engine require a raised-deck case to accomodate the large bore/piston configuration.
Largest bore your OEM cases can accept is a 3.812", and over a 4 5/8" stroke you can have a 106", or with a 5" stroke(not really suggested with a sock case if wanting to "lean" on it) it could be 114".
Scott

 

i was told its a merch performance cylinders pistons rings and heads that fit an evo motor thats bout all i know so far ill have to check and see what bore size is

 

Merch was a Canadian company who made scratch-built Evo style engines, up to 131" IIRC. I don't believe they are still around today. Bore size will certainly tell us if they will fit stock cases.

 

A 97" Evo can be had easily.
95 hp and 105-100 ft/lbs.
Scott