I replaced the battery in my 1977 Plus 8 (which I think is supposed to take a type 049) with the following

S4 023 Bosch Car Battery 12V 45Ah Type 049 S4023

but I had to modify the retaining clamp slightly to make it fit. (Disappointingly, it was supposed to have a rating of 330 CCA but it only measured 295 when it arrived - but it seems to work fine).

So the moral of the story is to measure the size of the battery holder/retaining clamp and check it against the dimensions of the battery you intend to buy before you actually buy it.

Dave
Blue 4/4 1969, Green +4 1953, (different) Green +8 1977