OK with the chassis apart I mount the rear bearing cassettes before I do anything else why you ask. Because its just what I do. No paticular reason other than the parts are easier to handle while apart. It is very important to mount the holders so when everything is assembled it is in direct line with original transaxle. US says you can move the axle up but not forward or rearward. So this is waht we do to lower the chassis.
You want to make sure that both sides are the same in the case of this chassis I measured from the front of the frame side panel to the front edge of the cassette holder, (28-7/8 ) and from the top of the side panel to the top of the holder (2-1/4) and be sure you have it square to the frame. All these measurements are decided using the shortest tire I run. And if using adjustable cassettes you will generally have as much as 3/8 up and down adjustability in your ride hieght.
