I wonder if there are any alternatives of gurochan where guro and loli is allowed.

Here is the list of whast I know:

For viewing pictures pixiv and exhentai are usable alternatives, but they do not have much of interactivity

there is also lolicit forum where Guro can be posted on the separate section but almost nobody is interested in anything unusual and unless you are pedophile you have nothing to do there because all content is ultra-realistic
On top of that, it is very hard to get in while easy to get banned if for some reason mods dislike you.
Unlike other forums, non lolicon stuff is forbidden there.

thedarkspot, dolcettgirls, Dolcettish do not alow lolicon content.

thedarkspot is owned by asshole admin tyrant who filled entire FAQ bragging about now tyrannical he is.

dolcettgirls seem to have somewhat decent admins and good diverse content on consensual guro side, but it is largely paysite.

Dolcettish seems to be adequate in terms of friendly atmosphere and so far most friendly staff, but it is mostly about hangings and beheadings.