I've A1200 with internal CD-ROM and 160GB hd, it was really thight to fit but it can done. It also have Apollo 040 with 32mb ram
SDHD card would make task simplier.
There is internal scandoublers, even new ones from Individual computers, but it would make installation very thight??
As a display I use LCD-TV with scart connetor, it gives me perfect flicker free picture, even hi-res laced modes. Benefit of that is I can connect to same tv 3 different amigas in same time.
Only benefit of scandoubler (Individual computers version) is higher resolutions, wich are bog slow.
So IF you are from Europe, LCD-TV with scart connector is obvious choise, if your are Nort America there is still some possibilities get some Dell etc monitor wich accepts NTSC modes through D-Sub connector
Installation is easy IF you have working hd installation of wb allready? Just connect two hds to one cable and make SDHD visible with your working installation.
Another easy way is use WinUEA to it