But you are missing the explanation of why. The original poster is in Europe, where he pays over $6 per gallon (Euros, Kilometers, and liters converted). I've been there and done that. I get it.
5000 miles per year at 9 MPG * $6.50 = $3611 / yr
5000 miles per year at 11 MPG * $6.50 = $2954 / yr
Difference is $656 / yr.
A 3 year return on investment is considered worth doing in most business models. So spending $1969 to get there would be considered good business.
EFI conversion will cost too much, unless there is some other driving factor where you can get two birds with one stone.
I do think I read where there are some distributors out there that you can program a timing curve into them, similar to EFI. I don't no the cost.
I do think the cam swap is very doable on that budget. However this depends on what the existing cam is.
Changing
oil is just routine maintenance.