I once fitted a 1100cc engine in my '77 TL. It was pretty well a straight swap, but the handbrake got in the way of the fuel filter. I took the radical step of moving the handbrake across to the other side of the car and it never worked correctly again. There is probably a better solution.
The TL bonnet stays foul the larger GTL radiator. I cut them off and had a floppy bonnet. Also the bulkhead needed to be hammered a bit on the RHS to clear the rear of the engine and allow acces to the oil filter. The little drum brakes on the TL weren't up to the 1100 either.
Thats all for a pre-'79 TL. I have a feeling yours is a later one with the GTL body? If so you won't have these problems.
To swap engines you'll need to remove the bonnet, pull the front suspension apart to remove the driveshafts, then unbolt lots of things and eventually you can pull the engine out. You'll need the complete 1100cc engine and gearbox with carb, starter etc, hoses and possibly radiator (I'm not sure if your car will already have the later radiator). Otherwise it should be a straight swap. The suspension springs are the same, so the heavier 1100 engine will give the car a nose down attitude. The driveshafts are the same. Even the speedo drive ratio is the same so the speedometer will still work.
An engine swap will tend to take me a weekend. Don't forget to put a new clutch in and unseize that clutch lever while the engine is out.
Oh, yes happy St Patrick's day.
