Suggestions on fix

I have a 1970 honda 175ss, when i bought it I was told it was mostly the top end of the engine rusted out, but upon futher inspection ive figured out that the engine was probably blown as well, and i figure that’s probably a grand to fix maybe more. Any suggestions besides just the full rebuild? Idk if a swap or something may be worth it, or where id even acquire an engine that fits.