Yeah! this is more or less what we have done.
The frame is based on a Lotus 11 series 2 which is very like the early 7. We use a Sunny back end and 1000 wagon diff (alloy carrier, v. light). We have Gemini uprights and calipers with 1600 discs ( the conversion was so easy it was amazing). The engine is a bored A14 (1472cc) with a fairly big head, Wade 140 cam and twin 44mm Mikunis. It weighs about 430-440 Kg. We run a close ratio O/D 5 speed and it goes like the clappers. More info can be provided if you are interested, because they are not hard to build