Identifying K-series 1.4 engines. How?

Hi.
I'm new round here and looking to find a Libra or K3 to play with.  One snag is that I know very little (nothing) about K-series engines so need help in identifying the various versions.

Google tells me the 1.4 engine (the one I'm most likely to get it seems) comes in various forms with 75, 82, 90 or 103 BHP, all are twin cam and some have VV so it's quite confusing to me.

I suppose the engine code ought be best guide to identification but I find conflicting information on the internet so shall be grateful if someone will direct me to a reliable source for code interpretation.

Also, the engine code may not be clearly visible so are there any other give away features on the engines to indicate what engine version I'm looking at?

I'm going to look at a K3 said to have MG Metro 1396 donor engine so will be grateful for any information on that particular engine (HP?, VV type? etc).

Thanks.