1.6 will only help not hurt in any way. Just slap the stock rockers on it and sleep well at night. I too have an XE268 with magnum heads on a 360 in my 68 cuda, 2.76 gears and stock 318 2bbl tq converter and it does not lack any TQ off idle even with an M1 single plane intake. Your cam is several sizes smaller and you have a dual plane intake so low speed TQ will not be an issue with the factory 1.6 rockers. If you want to run the chevy rockers you will also need guide plates that are magnum specific or some kind of adjustable ones, the stock ones don't use any of that junk.