JOWETTJAVELIN- I feel your pain. I ran a bearing in my 803 at junction 25 on the M1, fortunately close enough to Trowell Services to limp to safety in a pool of oil and mashed bearings... I gather at least with teh side valve, at least it will take 'enthusiastic' driving, so you can make a bit of progress. The 803 engine was known to be hopelessly weak even when it was new- we can both verify this!
Re the 948 running gear- I paid £100 for a second-hand engine, £35 for a gearbox (better ratios) and £40 for a differential. They were all second-hand, bought from my local Minor specialist, who promised that if any of the items were found to be no good after fitting, he would replace them free-of-charge. If you want to keep the 'magic wand' gearstick, a bit of jiggery-pokery is required, as the 948 box has a remote shaft, which means the gearstick is in a different position (there are threads detailing the changes needed, but it's not desperately hard to do). Alternatively, you can just swap the panel over the gearbox (under the carpet) with one from a Minor 1000, as the gearstick 'hole' is then in the corresponding position to that of the new gearstick. It does make the car look 'wrong' in my opinion though. If you want to go down this route, find a local Morris specialist- they quite often have spare engines etc- that's what I did. The cost will increase a lot if you have to get someone to do the work for you though- it took me a couple of days of messing around to change everything over (I'm not the speediest worker!). I suspect you'd be looking at a couple of days labour charges to pay someone do it right. Regarding suspension, brakes etc, there are no changes needed whatsoever- everything literally slots straight in (unless you have a pre-53 SII which I believe has the Nuffield type rear axle with a different diff- mine was a '54 with Cheesgrater grille and had the later Austin type axle, which made changing the diff a doddle). I loved my car after I'd made these changes to it, and still regret selling it! The 948 is a lovely sweet engine, though not quite as powerful as the 1098.
those of you who are purists should want to stop reading from this point on... to get a flathead or any other v8 into a minor you are going to have to fabricate a seperate chassis. forget a 1275cc if you want to go fast only a v8 will do. as for brakes forget 4 stud princess calipers. you are going to need 5 stud brakes granada or mustang will do and ford 5 stud opens up lots of wheel choices too. as for front end most hot rodders are using the mitsubishi L300 van front end as its a lot cheaper and easier to source than the mustang II front end. as for differential the choice is yours. jag xj6 (shafts will need shortening) ford zephyr mk4 or Toyota hilux (poor man's 9 inch ford)
It would certainly be very interesting if some brave soul would transplant a Ford flathead V8 into a Minor, and make a refreshing change from the usual Zetec/Duratec/Fiat twin-cam/Peugeot/Isuzu turbodiesel/Datsun 1200 transplants.
Of course, it would be utterly pointless, unless one wanted to prove the point that one could actually be fitted.