I would try to avoid such modification. The risk of damaging seems to be high. I would try some kind of extension cables and IDE to SATA adaptor. Or try to get a V12/V13 PS2 and modify it with hd combo. The inside of the hd combo has more space for IDE/SATA adaptors and additional extension cables.
PS2 SCPH-70004 V12 PAL + HDCOMBO + 160 GB Samsung HDD + OPL 0.9.1
PS2 SCPH-70004a V13 PAL Satin Silver
2 x Official Sony 8mb card +FMCB 1.8c + uLE 4.42b
Datel Max Memory 32mb card +FMCB 1.8b + uLE 4.42
Memor32 + Memento FW 1.2e