I would say that the OP is right to count an extra 1.5 syns. I have trawled high and low for a 57g roll and only recently Tesco brought out a 57g roll which is exactly HEXb compatible, hurrah for Tesco.
However, Hovis rolls have around about 40 cals and a little more sat fat in than other rolls (eg, I was in Asda and compared them to another wholemeal roll, which was 64g but around 40 cals less and 0.1 less sat fat)
So OP – to stick 100% to plan do your wisely worked out 1.5 syns OR pop along to Tesco to get your Healthy Living/Healthy Eating (I can never remember which it is) wholemeal rolls for 99p for 6.