akima interpolation for irregular grid - r

Question

I am trying to interpolate a irregular raster grid to a regular grid using akima library in R. However, after I define the regular grid and interpolate the values to the new regular grid, I end up in a strange raster position. I'm doing something wrong but I don't see where. If anyone has a solution (or know a different approach), please let me know. Thank you very much.
library(raster)
library(akima)
library(rgdal)
library(sp)
# download the file
url <- 'https://downloads.psl.noaa.gov/Datasets/NARR/Derived/monolevel/air.2m.mon.ltm.nc'
file <- paste0(getwd(), "/airtemp.nc")
download.file(url, file, quiet = TRUE, mode = "wb") # less than 4 mb
# define the grid edges according to https://psl.noaa.gov/data/gridded/data.narr.monolevel.html
y <- c(12.2, 14.3, 57.3, 54.5)
x <- c(-133.5, -65.1, -152.9, -49.4)
xym <- cbind(x, y)
p = Polygon(xym)
ps = Polygons(list(p),1)
sps = SpatialPolygons(list(ps))
# create a spatial grid to 0.3 cell size
xy <- makegrid(sps, cellsize = 0.3)
xy$first <-1
names(xy) <- c('x','y',"first")
coordinates(xy)<-~x+y
gridded(xy)<-T
# read the netcdf file and extract the values
cape <- brick(file)[[1]] #get the first layer only
rp <- rasterToPoints(cape)
rp <- na.exclude(rp)
# interpolate to the crs for Northern America Conformal Conic
r2 <- project(rp[,1:2], paste('+proj=lcc +lat_1=20 +lat_2=60 +lat_0=40 +lon_0=-96 +x_0=0 +y_0=0 +datum=NAD83 +units=m +no_defs'), inv=TRUE, use_ob_tran=TRUE)
# add the transformed coordinates
rp[,1:2] <-r2
rp <- as.data.frame(rp)
# create a spatial points object and plot it
coordinates(rp)<-~x+y
spplot(rp, scales=list(draw = T))
# interpolate the points to the coordinates (takes a while)
akima.sp <- interpp(x = coordinates(rp)[,1], y = coordinates(rp)[,2],
z = rp#data[,names(rp)[1]],
xo = coordinates(xy)[,1],
yo = coordinates(xy)[,2],
linear = F, extrap = F)
# create a raster file
r.a <- rasterFromXYZ(as.matrix(data.frame(akima.sp)))
plot(r.a)