If you are planning on getting larger radiators, then i would not get the H50 because you will have to do some major modding in order to hook a 240mm radiator up to you h50. It is meant to be used as is and not be upgraded. i.e it is sealed.
If your going watercooling, do it properly, You'll need alot of time to research it and also about £150-£200 for a good CPU loop, Don't go for cheap watercooling like the GIGABYTE GH-WIU02 3D Galaxy II Liquid Cooling kit.
If you don't have that kind of money then go for high end aircooling.
I have been thinking for a while about a configuration and this is what I think is the minimum to get a really good water cooling system (cpu only). And I am not using the components that I would like to.
CPU Watercool: HK Rev 3.0 LT Socket 1366 49,95 €
Pump: SWIFTECH MCP355 59,95 €
Pump adapter: EK EK-DDC X-TOP V2 ACETAL - ACETAL white 18,00 €
Reservoir: EK EK-MULTIOPTION RES 150 Rev.2 34,95 €
Reservoir adapter: EK EK-ANTI-CYCLON for MULTIOPTION SERIES 2,50 €
Radiator: Alphacool NexXxoS Xtreme III 360 Rev.2 49,95 €
FANS: 6 x SCYTHE ULTRA KAZE 3000rpm 120x120x38 59,40 €
Fittings: 8 xFESER G1/4 12.7mm. 45º 47,20 €
2 x PHOBYA G1/4 19/12.7 mm. 5,40 €
LIQUID: PRIMOCHILL PC-ICE blue UV 21,70 €
TUBE: 2 x TYGON R-3603 19-13 mm. 21,20 €
Final price:370,19 €
I wouldn't buy anything less than this (and maybe there is something that now I am not taken into account...)
Heater cores are very capable of removing heat. Unfortunately they are a very dense thick fin design and need LOUD high CFM fans to work properly. You laso need to make a shroud for them, usually cardboard, bits of metal/wood and tape.