petrol and Deisel block Differences

hiya people, I am a newbie to the site and the world of Land rovers I am currently working at restoring a 1977 series 3,... 2,25ltr petrol land rover along with its engine (obviously) however, the I have bought a 2.25 diesel engine off ebay that seems to be in better condition. my problem is......I have been told there is a variation in the internal structure of the diesel block, something about a hole to many either in the petrol block or the diesel, jeeez I'm even confusing myself now! If there is a difference can anyone tell me which engine block it is and its function..............The Engine blocks have the same part no and appear to be the same configuration. am I just being wound up or is it factual. would really appreciate some input.

My understanding is that engine blocks are the same, but pistons etc different. I'd stick to petrol if you do swop blocks.

Thanks jofn,
the intention is to stick with petrol but using the Deisel block

When I stripped down the Engine 2 of the pots were frozen solid making the petrol block almost useless, had to hammer the the old pots out.