Quite a few Tiger owners are converting their cars to the larger 289 or 302 engines. I will try and point out a few of the pitfalls and try and save you some time and money.
All 260 engines have what is described as a 5-bolt bell housing. The easiest way to fit a 289 is to try and find an early 289 which will be of 5-bolt design and therefore fit straight in with no problems. These 289 engines are, however, usually hard to find because they were made in relatively small numbers (as during 1965 Ford brought out the 6-bolt 289.
If you have a 6-bolt 289 or 302 what you also need is a 6-bolt bell housing. Most people use the flywheel off their 260 which uses a 10 1/2" clutch. Therefore you need a bell housing which was designed for that size clutch. If you get one with an 11" clutch, the starter motor will not mesh with the ring gear or flywheel.
The following part numbers are of aluminium 6-bolt bell housings which you can use with the 10 1/2" clutch:
I know these fit as I have used them, and there are more available (compared to a 5-bolt 289 engine).
The next problem encountered is the size of the hole in the bell housing, where the gearbox front retainer fits. All Tigers (except MkIIs) have a 4-11/16" O/D retainer - the bell housing is 4-7/8". The best fix is to buy the larger retainer; alternatively get a ring machined to fit between the retainer and the bell housing. It is now a simple matter of drilling the bell housing to suit the bolt pattern of the gearbox (a MkII gearbox will bolt straight on).
The final detail is to buy a clutch slave cylinder bracket for a 6-bolt bell housing. This looks just like a 5-bolt but will fit the 6-bolt.
On the engine size I find it best to use the aluminium timing cover and water pump off the 260 engine.