Crane CRN-753905 camshaft $110 from Summit Racing
Crane CRN-99278-12 lifters $74 from Summit Racing
Mopar Performance 5249464 valve springs $114 from
Moparts Racing
Mopar Performance 4452032 spring retainers $108 from
Moparts Racing
Mopar Performance 4529218 valve keepers (2 packs) $24 from
Moparts Racing
Melling high volume oil pump MEL-M167HVS $72 from Summit Racing ($139 from Hesco)
Cloyes dual roller timing set CLO-9-3127 $113 from Summit Racing ($149 from Hesco)
You'll also need injectors that flow 20% more than stock. Depending on what year is your XJ, you can find the appropriate injectors at
http://www.fiveomotorsport.com or in Ebay. Hesco will charge you $300 for a set of six injectors whereas you'll get them for half the price elsewhere.
As far as the aluminium head goes, you can buy it from Summit Racing under part no. PAR-1075 for $1350. Even the assembled head (you don't need it) costs $1500 which is $350 less than what Hesco charge for the same thing.
Finally, Hesco's stroker kit costs $2570 while Speedomotive's costs just $675. OK so you don't get as much in Speedomotive's kit but $1900 is still an awful lot of change! I built a whole stroker engine for just $1500 from a rebuildable core and I have my old 4.0 engine as a spare, so that gives you an indication of how much money you can save by shopping around and cherry-picking parts.
Food for thought.