Engine Desgin

This is the part the interests me the most the video's so far look brilliant.
So say i have built a 3.5 v8 for use in my luxury 4x4
Then say I decided to make a sports car i already have a 3.5 v8 which I can use great but its been made for a 4x4 with different demands to my sports car
So can I adjust and rework it to suit my sports car and bring out a b spec version of the engine without large costs etc?
Also does this work with new tech i.e. i make a engine then 5 years down the line new tech comes out allowing me to make a b spec of that engine with more bhp etc?
Also is it possible to buy engines off the ai? This happens alot in real world vauxhall/opel haven't made a diesel engine since the mid 90's and have brought 4 or 5 desgin's from both izuzu and fiat
So say i have built a 3.5 v8 for use in my luxury 4x4
Then say I decided to make a sports car i already have a 3.5 v8 which I can use great but its been made for a 4x4 with different demands to my sports car
So can I adjust and rework it to suit my sports car and bring out a b spec version of the engine without large costs etc?
Also does this work with new tech i.e. i make a engine then 5 years down the line new tech comes out allowing me to make a b spec of that engine with more bhp etc?
Also is it possible to buy engines off the ai? This happens alot in real world vauxhall/opel haven't made a diesel engine since the mid 90's and have brought 4 or 5 desgin's from both izuzu and fiat