Bolt straight on but best to put in a new cam/bearing and lifters while apart.

No need for splitting the engine case. 103 cylinders and pistons replace the 96 ones. Cylinders are just a bigger bore for the bigger piston. Heads are the same except for acrs are plugged into the 103 heads. You’d be mad not to change the cam whilst doing this so choose a good bolt on cam to suit (Andrews 48) and replace the inner cam bearing. Adjustable pushrods will likely be required and are recommended. Change the lifters whilst it’s all apart for better ones. Thinner head gasket (30 thou) will provide better quench and provide a little more compression 

The Andrews 48 cam will ensure lots of torque early and in mid range; perfect for the extra weight involving a side car

The 103 heads you got should already have the ACRs installed unless taken out. There’s some wiring that’s a giveaway if you have them. Worth having for cams that change your compression requiring additional cranking effort when starting. Otherwise s&s make ezy start cams that are a bit extra.  

If there is a hole basically in the middle of the head, thats for the ACR's. Otherwise it might already have the large block off bolts installed.

Just bore it to 103 with your current cylinders. Save money, same result. 

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