1964 midget engine

The plate that is supposed to be on my 1964 midget engine is missing

Are there ways that I can confirm which engine i have in the car ?

Well if if has lifter covers on the carbs side of the engine it is a 948 or 1098, and if a 948 it will be cast "950" on the side of the block. If no lifter covers behind the carbs, then you have a 1275.

There is a plate riveted to the lower side of the block under the carbs close to the crankshaft that says "1100"....so does that mean 1098 ?

YEP.

If it has a mechanical fuelpump, it's a 10CG engine from a late Mk1 Midget/Mk2 Sprite (GAN2/HAN7).
If it has no opening for a mechanical fuelpump but the mounting plate is cast on the side of the block plus only one mounting stud, it's a wide bearing 10CC engine from a later Mk2 Midget/Mk3 Sprite (GAN3/HAN8). Both are 1098 cc capacity of course.
Hope this helps.

Following this line of thinking, I think I have a 1098 Morris Minor motor. It has side covers under the carbs, 950 is NOT cast into the side of the block, MOWOG 3 is. 077 also, and 12A497, and H22.
The mechanical fuel pump has 2 mounting bolts, the valve cover says "Morris".
I need an exhaust manifold and exhaust system, so I think I'll go with headers and an aftermarket system.