I'm not questioning that you've noticed a difference, in the performance, but there could be a couple of reasons, which may not be related to the timing chain at all.
1. Did you ensure the little location pin between the back of the camshaft sproket & the front of the camshaft was reinstated, when you fitted the sproket to the camshaft ?
The crankshaft sproket has a giant keyway, that locates crankshaft pulley & the timing chain sprocket. The camshaft sprocket does not have a key, but a pin, that it relys on totally to lock the camshaft & chain, in the correct position. There have been those on here, that have had this pin shear, with dramatic results.
2. Did you replace the tensioner at the same time, as I assume you had a kit with it in ?
3. It could be that with the sloppy old chain, & a tensioner not working well; that the timing was out enough to effect the performance slightly, as the cam shaft drives both valves & the distrubutor; & hence has a slight effect on the ignition timing.
It could be that you have to adjust the ignition timing slightly, in both directions, in increments, & see whether it makes any difference. Have you got a timing light ? That could throw up the fault, as it will indicate, whether the automatic advance/retard mechanism is working OK.
Have you got a standard points type distributor ? Maybe it is time to give that an overhaul ?
Let's know what you find.
Trust this assists.
Cheers Banjo