Not sure if it's a bargain or not, but it's here: http://www.blatchat.com/t.asp?Id=128886

"1977 711M block, 1600 Kent engine.

Completely unmodified.

Sold without ancillaries apart from water pump. Includes flywheel and choice of rocker cover.

£300ono"

£300 !
You've got to love his optimism.

is that a realistic price? Heck, i've got one for sale if it will go for that much!

771 M is the better block for tuning and such but as for the price tag the best I would go is around 150 yo 175 max as I got my cossie for 400 inc turbo