If we can add Canadian tankers to the ANZAC party we can very easily get Valentines to Malaya in time, though it will be very tight.
Here's a pic from Nov. 1941 of the first batch of sixty-odd Canadian-made Valentine tanks to ship to Russia. Instead, let's get these produced in August and shipped via rail to Vancouver and then via merchant ship to Singapore, arriving end of October. According to
http://www.sea-distances.org/ Vancouver to Singapore at 10 knots takes just under 30 days. If 12 knots can be done, the voyage is now less than 25 days.
Ship them also with Colonel Worthington and crews from the Canadian Armoured Corps (plus the two Canadian regiments sent to HK),
https://en.wikipedia.org/wiki/F._F._Worthington.
Fifty or sixty Valentines won't guarantee a win, the IJA for example deployed over 200 of their tanks (albeit highly inferior to the Valentine). Also the Valentine's two man turret (see below pic, where commander has to load the gun) and lack of a HE shell and lack of hull mg would be frustrating to the anti-infantry actions, though the coaxial 7.92 Besa MG would be a true killer vs. bicycle or foot infantry.
Some logistical challenges may be felt, as the Canadian Valentines used US-sourced diesel engines and unusual mg calibre, with supply of fuel, ammunition and more likely parts causing some difficulties. However one can imagine the good feelings timely arrival of Valentines and their crew would convey to the garrison.
However, all this is useless if the tanks don't arrive on time, as seen at
http://1942malaya.blogspot.ca/2009/07/tank-squadron-that-came-too-late.html Maybe that's a good ATH discussion - have these tanks arrive two months earlier.