You said it urself, they have links from ghor. Also you should know tribal areas have never been part of KPK, untill recently. These are overlapping areas. My point of pashtuns not being indigenous to KPK stands and its u backtracking and finding excuses. Almost every tribe find its roots outside KPK. Visit pashto deppt of Peshawar university and u can get some knowledge abt pashtun history. What gora sahab wrote is not ultimate truth.
Let me tell u another pashto scholarly debate, it is that khattaks are not pashtuns, though khattaks disagree, many pashto scholars believe so because khattaks can not trace their lineage or tribe to Afghanistan. They were also mughal allies and against most pashtuns.
Balochistan is scarcely populated today, so one can wonder how it was one or two thousand years ago, i have not backtracked but balochistan is more complicated because all are not pashtuns and i dont know much abt local tribes. The achakzai and other pashtuns all claim to have migrated from Afghanistan.
The very fact that they converted in such a short duration means they were not forced and werw not budhist. Only monotheists quickly accepted Islam as it coroborated with their already established beliefs. Budhists have always resisted conversion.
Why would anyone feel embarrassed by history? I guess its u with that notion in mind, hence rejecting the local knowledge and believing what 28 yrs old British surveyors wrote, who couldnt even speak the local language. My aim here is to give the ground reality perspective and what the local history tells us. I doubt anyone of u have ever read a pashto history book.