engine swap 87 civic si help

the car is a 87 honda civic si 1.5 engine number is d15a3 so it says.


i was wondering if anyone had like step by step on on what engine i could swap out with out mods. and would i need to change like the ecu when i do change out an engine. i heard like integras or somthing would slid right in. but what about the trannny? what would bolt right up to it.