Terrier number is in the same place as a P76 Dave.
Printable View
OK here is the engine number: 48DO1039A
https://www.aulro.com/afvb/images/im...017/07/783.jpg
This tells us it's a 4.6
48D = 4.6 from P38A. It should have cross bolted mains.
Rover V8 Engine Numbers
Yes, just looked it up, and can confirm that it also has the bolted cross mains.
Result
If you are going to pull the sump off for some reason, you can confirm it is a 4.6 as it is cast into the front crank counter weight - however the number and cross bolted mains would be good enough evidence for me.