What year model is your ute?
If it is up to 1973, then the original engine will have the distributor above the oil pump & you will need to either modify the engine mounts to pick up the more forward placement of the towers on the crossmember or,.... find a crossmember from a 1974 or later ute & fit that instead.

If your ute is 1974 or later, you should have no trouble fitting the A15 into the engine bay as the crossmember will have the towers in the right place for these later engines.

An easy brake upgrade is to either use the complete strut assembly from a 1200 coupe, or get a pair of struts from a 120Y. Avoid the Australian assembled sedans from July 1976 as the disc brakes on these are completely different.

I recomend that you take the chance to slip a new pair of shock absorber inserts into the new struts while you can & if you want to lower the front a little, then some King springs should do the trick. Lastly, use the top piece from your 1200 suspension as these are different from the 120Y item & will leave your 1200 sitting a bit high. Use the 1200 ones to get the ride height right.
ALWAYS use a set of spring compressors when working on front springs as they can cause a lot of pain if you don't, so buy, rent or borrow some, but use them.

Now would be a good time to either overhaul or replace your master cylinder as the drum brake version will need to have the residual pressure check valve removed from the front brake circuit [but not the back] or a new 1200 coupe item will have that done already.