Power Hack Saw help needed

[garage nut]

Looked at all the different ideas on here for making a "Power Hack Saw".
Ended up liking the idea of the one with a frame at the back more than the conventional "Slide" type.

Think there is going to be too much play on the slide and if you set it tight enough to stop the play a lot of power will be used just to overcome the friction.

Has anybody got some dimensions for this type of saw?

Basic givens...
300mm x 25 Starett 14T blade
Stroke 200mm to use maximum of the blade.
That means the crank moving the blade has to be 100mm.
That dictates that the pivot for this crank must be about 120mm above the base plate.
Link from crank to saw blade frame also about 120mm.

Just going to cut this all 1:1 from cardboard and figure out the frame and rear frame dimensions.

Was thinking of using bearing ends as the bearings of the rear frame, setting them up so I can use their tread to fine tune the saw to cut square.

Anything major I am missing?