Wheel Base is 76mm - center to center measurement
Width is 19mm for the rear axle bracket and the front motor mount bracket - over all , the chassis flat width is relieved to 17.6 mm between those brackets ,
After the motor bracket mount to the front is 17.6 mm all the way including the front axle brackets .
The Revell 1/24 midget kit Body is slightly narrower than EJ's body so it may be best to go 17mm or less at the front for the front section,
The chassis base is 73.2 long - not counting the guide tongue.
Overall for front to rear axle bracket extreme length is 83mm.
The Oillite bearing holes are 4.5 mm
The rear axle bracket is 15.4mm wide at the base . The front axle bracket is 12.2 & the motor mount bracket is 11.3 at the base
25mm between the rear axle bracket to the Motor mount bracket
10mm between the motor bracket and the front axle bracket
45mm between the front & rear axle brackets
9 mm from under the chassis to the bearing hole center of both front & rear axle brackets .
4mm from under the chassis to the motor bracket hole .
Rear motor bracket is 16 mm high from under the chassis.
The motor shaft center is 8.3mm above the bottom of the chassis and is a 6mm hole for the motor bearing .
The 2 motor mount screw holes are 10mm apart & central to the motor shaft . They are 2mm holes
The guide hole center is 8 mm in front of the front axle center line. The tongue is about 10.4mm wide at the chassis base .
The body mount screw elongated hole center id 9.2mm behind the center line of the front axle .
The guide post hole is 4.7mm
The front motor bracket is 17.5 mm overall width - to fit inside the chassis at the mounting bracket
It is 11mm wide across the bracket .
The motor bearing loop is 10mm wide . The bearing hole is 6 mm diameter. The bearing hole id 7.5 mm above the underside of the bracket .
The chassis screw holes are 3mm above the underside of the bracket .
Well I think that is all you need to draw up planes or even make the chassis .
If not ask me for more details. - The brass plate is 0.8mm thick for the chassis & the bracket .