Small vs Large 100 Block?

[rekcuftar]

I have a mid 80's 2cyl OMC I bought for a Lake toy project. I have seen references to both the large and small 100 blocks. What is the difference? What is preferred? Why? How do I know which I have?

[OUTBOARDER]

I have a mid 80's 2cyl OMC I bought for a Lake toy project. I have seen references to both the large and small 100 blocks. What is the difference? What is preferred? Why? How do I know which I have?

if you are going to re-build , remove sleeves and port, they are all equal after porting.
Let me know and I can dig up a rec porting template for you.