https://www.youtube.com/watch?v=A-x-7IkmoC4 This is at 1080p (3258+730) and it almost handles it - lowering the ress at 1360x768 should make it run at above 60 constantly.
http://www.tipidpc.com/viewreview.php?id=1107 This is at 1366x768 at max settings and the gt 730 is getting 56fps AVG with dips to 42 - this is however limited by the slow celeron dual core at 2.6ghz - your pentium clocked at 4.2ghz should remove this limitation and grant you 60fps.
Also intel is targeting the g3258 specifically for LoL and Dota2:
http://www.technologyx.com/pc-hardware/intels-pentium-g3258-budget-overclockers-dream-big-bust/
So if you plan on playing Dota2 at 1366x768 then go with the g3258 + geforce 730 HOWEVER if you think you'll play at a higher resolution in the future (like 1080p and still want 60 fps at max settings) then go with an r7 260X or if you insist on nvidia then a 750ti, otherwise at 768p the 730 will be enough.