I am updating the Prima Conversion Pages, see the bottom menu item.

This adapter is for a Series IIa and III landrover gearbox, so it acepts the Perkins Prima engine; which is found in turbo form in Montegos and Maestros, in naturaly aspirated form in Maestros, LDVs and Sherpas. I don't know about fitting the normaly aspirated engines, in the Perkins drawings of a staitionary engine I can see they have a different oil pump and the filter will interfere with the engine mount, apart from that they look to have the same ancillaries and should fit.

Some of my drawings prior to making the adapter are online, as are pictures of the first of them being machined. Pictures taken during my own engine conversion apperared on some web pages, i have since deleted all last years photo's however - so if you take any photos I would be happy to add a gallery to this page,or link to them.
The early adapters were cast from LM4 and were in the as cast condition, this is the basic casting aluminium used in engineering, it is a good silicon aluminium with excelent properties, I was happy with them untill I started rolling the bellhousing stud threads, they didn't look very nice. I changed to LM25 and have also had them heat-treated to TF[T6], the rolled threads look better and the machining is nicer.
The machined casting weighs approx 6kg, this is what it should weigh according to Solidworks, I admit I have yet to weigh one.
The 3/8 UNC bellhousing stud threads are tapped with a thread rolling tap. The crest of the rolled thread may not look fully formed but the thread should be stronger and harder. They are also tighter than the usual tolerance, so you will find the studs stiff to put in, this is intentional. The thread should be clean, a slight bit of oil or loctite on the thread but none in the hole, they arent drilled much deeper than needed and oil in the holes will hydraulic and split the casting. If you loctite them in leave two opposite studs so you can pull them out and use long studs as dowels to help locate the engine on installation. The casting is drilled and tapped 20-25mm deep, if you damage a thread there is plenty of material to drill to 2 1/4 inches and put a longer stud in. The starter motor attaches with two ten mm bolt's. I used 10mmx35mm capheads, combined with a 3/8" wobble drive and allen key fitting, the bolt's are easy to install and tighten, I have removed the starter to check the dimensions and it was an easy task. I have repostioned the starter, I origianly positioned it to give me most clearance on the footwell. then the second lot of mounts I raised it as people moaned about fitting the breather to sump pipe. I have since lowered it as they said the wires were difficult to put on. Please give me feedback I will take notice of it. You will find a 12mm thread directly below the starter, a 12mm bolt goes through the block and into the adapter, if you took the engine out of the Montego you will find a suitable bolt among the bolts you have, the bolt could interfere with the ring gear so check the length. The bolt's inside the adapter that go into the block are 10mm x 35 mm approx, they are washer headed bolts and lot's of them were used on the Montego you need something like ten for the adapter - you also want 12 similar 10 mm bolt's for the engine/alternator mounts. You want three 8 mm bolt's, they surround the oil seal, all the ones i used came from the box of bolt's from removing the Montego engine.