I saw your title and miss-read/miss-interpreted it as 1/4 scale Farmall M. I grew up driving a Super M-TA, and I was thinking COOL - someone's building an a 1/4 scale M?
I was SLIGHTLY disappointed when I saw the picture, but you did a nice job on the castings. If that's a popsicle stick in the upper RH corner, instead of a tongue depressor, then you did a VERY nice job on those itty-bitty castings.
I made several engine before this from casting I made, the best way to make patterns is to have something to look at and scale down for the size When it comes to casting it you will have many failures. You should design your pattern for machining so it be held firmly in the mill to start
Anyone wanting to build an International M, but can't do the castings, Wismer Machine Company sell/sold castings and various other small bits for a 1/2 size engine. (Like many other suppliers, may no longer be in business. The model side was just a sideline to the main machining business.)