Listen, the thing to watch out for is noise every time you start up, dont drive off till its gone, if it stays noisy switch off and dont use till sorted as you risk it snapping.
If it starts getting noisy for longer each time, the same dont use your motor.
When mine got bad I wasnt aware of the chain issues and listening to the engine I initially thought just the water pump bearings had gone. The only real way of checking the chain is to take off the timing cover by which point your more or less half way through the time it would take to actually change it.
Has your new engine got the modified kit already in, has it got the slits in the tensioner as in marks photos.